diff --git a/UI/app.tsx b/UI/app.tsx
index b3e8da9..36440a7 100644
--- a/UI/app.tsx
+++ b/UI/app.tsx
@@ -14,10 +14,9 @@ import { MessagePanel } from "./message-panel.tsx";
 import { Setting } from "./setting.tsx";
 import { Database_Contextual_View } from "../database.ts";
 
-import { getAllUsersInformation, ProfilesSyncer, UserInfo } from "./contact-list.ts";
+import { AllUsersInformation, ProfilesSyncer, UserInfo } from "./contact-list.ts";
 
 import { new_DM_EditorModel } from "./editor.tsx";
-import { Channel } from "https://raw.githubusercontent.com/BlowaterNostr/csp/master/csp.ts";
 import { initialModel, Model } from "./app_model.ts";
 import {
     AppEventBus,
@@ -156,6 +155,7 @@ async function initProfileSyncer(
 export class App {
     profileSyncer!: ProfilesSyncer;
     eventSyncer: EventSyncer;
+    public readonly allUsersInfo: AllUsersInformation;
 
     constructor(
         public readonly database: Database_Contextual_View,
@@ -166,10 +166,11 @@ export class App {
         public readonly relayPool: ConnectionPool,
     ) {
         this.eventSyncer = new EventSyncer(this.relayPool, this.database);
+        this.allUsersInfo = new AllUsersInformation(myAccountContext);
     }
 
     initApp = async (accountContext: NostrAccountContext) => {
-        const events = this.database.filterEvents((e) => e.kind == NostrKind.TEXT_NOTE);
+        // const events = this.database.filterEvents((e) => e.kind == NostrKind.TEXT_NOTE);
 
         console.log("App.initApp");
         const profilesSyncer = await initProfileSyncer(this.relayPool, accountContext, this.database);
@@ -179,15 +180,16 @@ export class App {
 
         this.profileSyncer = profilesSyncer;
 
-        this.model.allUsersInfo = getAllUsersInformation(this.database, this.myAccountContext);
+        this.allUsersInfo.addEvents(this.database.events);
         console.log("App allUsersInfo");
-        this.model.social.threads = getSocialPosts(this.database, this.model.allUsersInfo);
+        this.model.social.threads = getSocialPosts(this.database, this.allUsersInfo.userInfos);
 
         /* my profile */
-        this.model.myProfile = this.model.allUsersInfo.get(accountContext.publicKey.hex)?.profile?.profile;
+        this.model.myProfile = this.allUsersInfo.userInfos.get(accountContext.publicKey.hex)?.profile
+            ?.profile;
 
         /* contacts */
-        for (const contact of this.model.allUsersInfo.values()) {
+        for (const contact of this.allUsersInfo.userInfos.values()) {
             const editor = this.model.editors.get(contact.pubkey.hex);
             if (editor == null) {
                 const pubkey = PublicKey.FromHex(contact.pubkey.hex);
@@ -206,7 +208,7 @@ export class App {
         }
 
         await profilesSyncer.add(
-            ...Array.from(this.model.allUsersInfo.keys()),
+            ...Array.from(this.allUsersInfo.userInfos.keys()),
         );
         console.log("user set", profilesSyncer.userSet);
 
@@ -221,6 +223,7 @@ export class App {
                     this.profileSyncer,
                     this.lamport,
                     this.eventBus,
+                    this.allUsersInfo,
                 )
             ) {
                 render(<AppComponent model={this.model} eventBus={this.eventBus} />, document.body);
@@ -261,7 +264,11 @@ export function AppComponent(props: {
     if (model.navigationModel.activeNav == "Social") {
         let focusedContentGetter = () => {
             // console.log("AppComponent:getFocusedContent before", Date.now() - t);
-            let _ = getFocusedContent(model.social.focusedContent, model.allUsersInfo, model.social.threads);
+            let _ = getFocusedContent(
+                model.social.focusedContent,
+                app.allUsersInfo.userInfos,
+                model.social.threads,
+            );
             // console.log("AppComponent:getFocusedContent", Date.now() - t);
             if (_?.type === "MessageThread") {
                 let editor = model.social.replyEditors.get(_.data.root.event.id);
@@ -354,7 +361,7 @@ export function AppComponent(props: {
                         myAccountContext: myAccountCtx,
                         db: app.database,
                         pool: app.relayPool,
-                        allUserInfo: model.allUsersInfo,
+                        allUserInfo: app.allUsersInfo.userInfos,
                         profilesSyncer: app.profileSyncer,
                         eventSyncer: app.eventSyncer,
                     })}
diff --git a/UI/app_model.ts b/UI/app_model.ts
index 6a10b62..5fbaaf8 100644
--- a/UI/app_model.ts
+++ b/UI/app_model.ts
@@ -24,7 +24,7 @@ export type Model = {
         key: string;
         value: string;
     };
-    allUsersInfo: Map<string, UserInfo>;
+    // allUsersInfo: Map<string, UserInfo>;
 
     // social
     social: {
@@ -57,7 +57,7 @@ export function initialModel(): Model {
             hasNewMessages: new Set(),
             currentSelectedContact: undefined,
         },
-        allUsersInfo: new Map(),
+        // allUsersInfo: new Map(),
         editors: editors,
         newProfileField: {
             key: "",
diff --git a/UI/app_update.ts b/UI/app_update.ts
index 322701f..017e160 100644
--- a/UI/app_update.ts
+++ b/UI/app_update.ts
@@ -1,7 +1,7 @@
 import { getProfileEvent, getProfilesByName, saveProfile } from "../features/profile.ts";
 
 import { App } from "./app.tsx";
-import { getAllUsersInformation, getGroupOf, ProfilesSyncer, UserInfo } from "./contact-list.ts";
+import { AllUsersInformation, getGroupOf, ProfilesSyncer, UserInfo } from "./contact-list.ts";
 
 import * as csp from "https://raw.githubusercontent.com/BlowaterNostr/csp/master/csp.ts";
 import { Database_Contextual_View } from "../database.ts";
@@ -27,7 +27,15 @@ import {
 } from "https://raw.githubusercontent.com/BlowaterNostr/nostr.ts/main/nostr.ts";
 import { ConnectionPool } from "https://raw.githubusercontent.com/BlowaterNostr/nostr.ts/main/relay.ts";
 import { SignInEvent, signInWithExtension, signInWithPrivateKey } from "./signIn.tsx";
-import { computeThreads, getTags, PinContact, UnpinContact } from "../nostr.ts";
+import {
+    computeThreads,
+    Decrypted_Nostr_Event,
+    getTags,
+    PinContact,
+    PlainText_Nostr_Event,
+    Profile_Nostr_Event,
+    UnpinContact,
+} from "../nostr.ts";
 import { MessageThread } from "./dm.tsx";
 import { DexieDatabase } from "./dexie-db.ts";
 import { getSocialPosts } from "../features/social.ts";
@@ -192,7 +200,7 @@ export async function* UI_Interaction_Update(
             };
             const group = getGroupOf(
                 event.pubkey,
-                model.allUsersInfo,
+                model.app.allUsersInfo.userInfos,
             );
             model.dm.selectedContactGroup = group;
             updateConversation(model.app.model, event.pubkey);
@@ -440,12 +448,13 @@ export async function* Database_Update(
     profileSyncer: ProfilesSyncer,
     lamport: LamportTime,
     eventEmitter: EventEmitter<SelectProfile>,
+    allUserInfo: AllUsersInformation,
 ) {
     const changes = database.onChange((_) => true);
     while (true) {
         await csp.sleep(333);
         await changes.ready();
-        const changes_events: NostrEvent[] = [];
+        const changes_events: (PlainText_Nostr_Event | Decrypted_Nostr_Event | Profile_Nostr_Event)[] = [];
         while (true) {
             if (!changes.isReadyToPop()) {
                 break;
@@ -460,7 +469,7 @@ export async function* Database_Update(
 
         let hasKind_1 = false;
         for (let e of changes_events) {
-            model.allUsersInfo = getAllUsersInformation(database, ctx);
+            allUserInfo.addEvents([e]);
             const t = getTags(e).lamport_timestamp;
             if (t) {
                 lamport.set(t);
@@ -470,7 +479,7 @@ export async function* Database_Update(
                 await profileSyncer.add(key.hex);
             }
             if (e.kind == NostrKind.META_DATA || e.kind == NostrKind.DIRECT_MESSAGE) {
-                for (const contact of model.allUsersInfo.values()) {
+                for (const contact of allUserInfo.userInfos.values()) {
                     const editor = model.editors.get(contact.pubkey.hex);
                     if (editor == null) { // a stranger sends a message
                         const pubkey = PublicKey.FromHex(contact.pubkey.hex);
@@ -547,7 +556,7 @@ export async function* Database_Update(
             }
         }
         if (hasKind_1) {
-            model.social.threads = getSocialPosts(database, model.allUsersInfo);
+            model.social.threads = getSocialPosts(database, allUserInfo.userInfos);
         }
         yield model;
     }
diff --git a/UI/contact-list.ts b/UI/contact-list.ts
index 5ebffe8..a54e241 100644
--- a/UI/contact-list.ts
+++ b/UI/contact-list.ts
@@ -1,5 +1,5 @@
 import { Database_Contextual_View } from "../database.ts";
-import { ProfileFromNostrEvent, profilesStream } from "../features/profile.ts";
+import { profilesStream } from "../features/profile.ts";
 
 import { Channel } from "https://raw.githubusercontent.com/BlowaterNostr/csp/master/csp.ts";
 import { ContactGroup } from "./contact-list.tsx";
@@ -13,8 +13,13 @@ import {
     ConnectionPool,
     newSubID,
 } from "https://raw.githubusercontent.com/BlowaterNostr/nostr.ts/main/relay.ts";
-import { CustomAppData, getTags, Profile_Nostr_Event } from "../nostr.ts";
-import { assertEquals } from "https://deno.land/std@0.176.0/testing/asserts.ts";
+import {
+    CustomAppData,
+    Decrypted_Nostr_Event,
+    getTags,
+    PlainText_Nostr_Event,
+    Profile_Nostr_Event,
+} from "../nostr.ts";
 
 export interface UserInfo {
     pubkey: PublicKey;
@@ -97,18 +102,18 @@ function socialPostsStream(pubkeys: Iterable<string>, pool: ConnectionPool) {
     return chan;
 }
 
-export function getAllUsersInformation(
-    database: Database_Contextual_View,
-    ctx: NostrAccountContext,
-): Map<string, UserInfo> {
-    const t = Date.now();
-    const res = new Map<string, UserInfo>();
-    {
-        for (const event of database.filterEvents((_) => true)) {
+export class AllUsersInformation {
+    readonly userInfos = new Map<string, UserInfo>();
+
+    constructor(public readonly ctx: NostrAccountContext) {}
+
+    addEvents(events: (Profile_Nostr_Event | PlainText_Nostr_Event | Decrypted_Nostr_Event)[]) {
+        // const t = Date.now();
+        for (const event of events) {
             switch (event.kind) {
                 case NostrKind.META_DATA:
                     {
-                        const userInfo = res.get(event.pubkey);
+                        const userInfo = this.userInfos.get(event.pubkey);
                         const profileEvent = event;
                         if (userInfo) {
                             if (userInfo.profile) {
@@ -126,7 +131,7 @@ export function getAllUsersInformation(
                                 newestEventSendByMe: undefined,
                                 profile: profileEvent,
                             };
-                            res.set(event.pubkey, newUserInfo);
+                            this.userInfos.set(event.pubkey, newUserInfo);
                         }
                     }
                     break;
@@ -139,19 +144,19 @@ export function getAllUsersInformation(
                 case NostrKind.DIRECT_MESSAGE:
                     {
                         let whoAm_I_TalkingTo = "";
-                        if (event.pubkey == ctx.publicKey.hex) {
+                        if (event.pubkey == this.ctx.publicKey.hex) {
                             // I am the sender
                             whoAm_I_TalkingTo = getTags(event).p[0];
-                        } else if (getTags(event).p[0] == ctx.publicKey.hex) {
+                        } else if (getTags(event).p[0] == this.ctx.publicKey.hex) {
                             // I am the receiver
                             whoAm_I_TalkingTo = event.pubkey;
                         } else {
                             // I am neither. Possible because other user has used this device before
                             break;
                         }
-                        const userInfo = res.get(whoAm_I_TalkingTo);
+                        const userInfo = this.userInfos.get(whoAm_I_TalkingTo);
                         if (userInfo) {
-                            if (whoAm_I_TalkingTo == ctx.publicKey.hex) {
+                            if (whoAm_I_TalkingTo == this.ctx.publicKey.hex) {
                                 // talking to myself
                                 if (userInfo.newestEventSendByMe) {
                                     if (event.created_at > userInfo.newestEventSendByMe?.created_at) {
@@ -163,7 +168,7 @@ export function getAllUsersInformation(
                                     userInfo.newestEventReceivedByMe = event;
                                 }
                             } else {
-                                if (ctx.publicKey.hex == event.pubkey) {
+                                if (this.ctx.publicKey.hex == event.pubkey) {
                                     // I am the sender
                                     if (userInfo.newestEventSendByMe) {
                                         if (event.created_at > userInfo.newestEventSendByMe.created_at) {
@@ -191,12 +196,12 @@ export function getAllUsersInformation(
                                 newestEventSendByMe: undefined,
                                 profile: undefined,
                             };
-                            if (whoAm_I_TalkingTo == ctx.publicKey.hex) {
+                            if (whoAm_I_TalkingTo == this.ctx.publicKey.hex) {
                                 // talking to myself
                                 newUserInfo.newestEventSendByMe = event;
                                 newUserInfo.newestEventReceivedByMe = event;
                             } else {
-                                if (ctx.publicKey.hex == event.pubkey) {
+                                if (this.ctx.publicKey.hex == event.pubkey) {
                                     // I am the sender
                                     newUserInfo.newestEventSendByMe = event;
                                 } else {
@@ -204,7 +209,7 @@ export function getAllUsersInformation(
                                     newUserInfo.newestEventReceivedByMe = event;
                                 }
                             }
-                            res.set(whoAm_I_TalkingTo, newUserInfo);
+                            this.userInfos.set(whoAm_I_TalkingTo, newUserInfo);
                         }
                     }
                     break;
@@ -216,7 +221,7 @@ export function getAllUsersInformation(
                     }
                     const obj: CustomAppData = JSON.parse(event.decryptedContent);
                     if (obj.type == "PinContact" || obj.type == "UnpinContact") {
-                        const userInfo = res.get(obj.pubkey);
+                        const userInfo = this.userInfos.get(obj.pubkey);
                         if (userInfo) {
                             if (userInfo.pinEvent) {
                                 if (event.created_at > userInfo.pinEvent.created_at) {
@@ -232,7 +237,7 @@ export function getAllUsersInformation(
                                 };
                             }
                         } else {
-                            res.set(obj.pubkey, {
+                            this.userInfos.set(obj.pubkey, {
                                 pubkey: PublicKey.FromHex(obj.pubkey) as PublicKey, // todo: could throw
                                 pinEvent: {
                                     content: obj,
@@ -247,17 +252,8 @@ export function getAllUsersInformation(
                 }
             }
         }
+        // console.log("AllUsersInformation:addEvents", Date.now() - t);
     }
-    // todo: should write a unit test for it instead of runtime assertion
-    for (const [pubkey, userInfo] of res) {
-        assertEquals(pubkey, userInfo.pubkey.hex);
-        if (userInfo.profile) {
-            assertEquals(pubkey, userInfo.profile.pubkey);
-        }
-    }
-
-    console.log("getAllUsersInformation", Date.now() - t);
-    return res;
 }
 
 export const sortUserInfo = (a: UserInfo, b: UserInfo) => {
diff --git a/database.ts b/database.ts
index f55d45f..ba8bd81 100644
--- a/database.ts
+++ b/database.ts
@@ -332,9 +332,11 @@ export class Database_Contextual_View {
     //////////////////
     // On DB Change //
     //////////////////
-    onChange(filter: (e: NostrEvent) => boolean) {
+    onChange(filter: (e: PlainText_Nostr_Event | Decrypted_Nostr_Event | Profile_Nostr_Event) => boolean) {
         const c = this.caster.copy();
-        const res = csp.chan<NostrEvent>(buffer_size);
+        const res = csp.chan<PlainText_Nostr_Event | Decrypted_Nostr_Event | Profile_Nostr_Event>(
+            buffer_size,
+        );
         (async () => {
             for await (const newE of c) {
                 if (filter(newE)) {