diff --git a/src/modules/coreFeatures/ModuleConflictChecker.ts b/src/modules/coreFeatures/ModuleConflictChecker.ts
index fde5640..46d201b 100644
--- a/src/modules/coreFeatures/ModuleConflictChecker.ts
+++ b/src/modules/coreFeatures/ModuleConflictChecker.ts
@@ -37,13 +37,17 @@ export class ModuleConflictChecker extends AbstractModule implements ICoreModule
     // TODO-> Move to ModuleConflictResolver?
     conflictResolveQueue = new QueueProcessor(
         async (filenames: FilePathWithPrefix[]) => {
-            await this.core.$$resolveConflict(filenames[0]);
+            const filename = filenames[0];
+            return await this.core.$$resolveConflict(filename);
         },
         {
             suspended: false,
             batchSize: 1,
-            concurrentLimit: 1,
-            delay: 10,
+            // No need to limit concurrency to `1` here, subsequent process will handle it,
+            // And, some cases, we do not need to synchronised. (e.g., auto-merge available).
+            // Therefore, limiting global concurrency is performed on resolver with the UI.
+            concurrentLimit: 10,
+            delay: 0,
             keepResultUntilDownstreamConnected: false,
         }
     ).replaceEnqueueProcessor((queue, newEntity) => {
@@ -57,19 +61,13 @@ export class ModuleConflictChecker extends AbstractModule implements ICoreModule
         new QueueProcessor(
             (files: FilePathWithPrefix[]) => {
                 const filename = files[0];
-                // const file = await this.core.storageAccess.isExists(filename);
-                // if (!file) return [];
-                // if (!(file instanceof TFile)) return;
-                // if ((file instanceof TFolder)) return [];
-                // Check again?
                 return Promise.resolve([filename]);
-                // this.conflictResolveQueue.enqueueWithKey(filename, { filename, file });
             },
             {
                 suspended: false,
                 batchSize: 1,
-                concurrentLimit: 5,
-                delay: 10,
+                concurrentLimit: 10,
+                delay: 0,
                 keepResultUntilDownstreamConnected: true,
                 pipeTo: this.conflictResolveQueue,
                 totalRemainingReactiveSource: this.core.conflictProcessQueueCount,
diff --git a/src/modules/features/ModuleInteractiveConflictResolver.ts b/src/modules/features/ModuleInteractiveConflictResolver.ts
index 8f2b4d5..c8a86ba 100644
--- a/src/modules/features/ModuleInteractiveConflictResolver.ts
+++ b/src/modules/features/ModuleInteractiveConflictResolver.ts
@@ -13,6 +13,7 @@ import { ConflictResolveModal } from "./InteractiveConflictResolving/ConflictRes
 import { AbstractObsidianModule, type IObsidianModule } from "../AbstractObsidianModule.ts";
 import { displayRev, getPath, getPathWithoutPrefix } from "../../common/utils.ts";
 import { fireAndForget } from "octagonal-wheels/promises";
+import { serialized } from "../../lib/src/concurrency/lock.ts";
 
 export class ModuleInteractiveConflictResolver extends AbstractObsidianModule implements IObsidianModule {
     $everyOnloadStart(): Promise<boolean> {
@@ -34,67 +35,71 @@ export class ModuleInteractiveConflictResolver extends AbstractObsidianModule im
     }
 
     async $anyResolveConflictByUI(filename: FilePathWithPrefix, conflictCheckResult: diff_result): Promise<boolean> {
-        this._log("Merge:open conflict dialog", LOG_LEVEL_VERBOSE);
-        const dialog = new ConflictResolveModal(this.app, filename, conflictCheckResult);
-        dialog.open();
-        const selected = await dialog.waitForResult();
-        if (selected === CANCELLED) {
-            // Cancelled by UI, or another conflict.
-            this._log(`Merge: Cancelled ${filename}`, LOG_LEVEL_INFO);
-            return false;
-        }
-        const testDoc = await this.localDatabase.getDBEntry(filename, { conflicts: true }, false, true, true);
-        if (testDoc === false) {
-            this._log(`Merge: Could not read ${filename} from the local database`, LOG_LEVEL_VERBOSE);
-            return false;
-        }
-        if (!testDoc._conflicts) {
-            this._log(`Merge: Nothing to do ${filename}`, LOG_LEVEL_VERBOSE);
-            return false;
-        }
-        const toDelete = selected;
-        // const toKeep = conflictCheckResult.left.rev != toDelete ? conflictCheckResult.left.rev : conflictCheckResult.right.rev;
-        if (toDelete === LEAVE_TO_SUBSEQUENT) {
-            // Concatenate both conflicted revisions.
-            // Create a new file by concatenating both conflicted revisions.
-            const p = conflictCheckResult.diff.map((e) => e[1]).join("");
-            const delRev = testDoc._conflicts[0];
-            if (!(await this.core.databaseFileAccess.storeContent(filename, p))) {
-                this._log(`Concatenated content cannot be stored:${filename}`, LOG_LEVEL_NOTICE);
+        // UI for resolving conflicts should one-by-one.
+        return await serialized(`conflict-resolve-ui`, async () => {
+            this._log("Merge:open conflict dialog", LOG_LEVEL_VERBOSE);
+            const dialog = new ConflictResolveModal(this.app, filename, conflictCheckResult);
+            dialog.open();
+            const selected = await dialog.waitForResult();
+            if (selected === CANCELLED) {
+                // Cancelled by UI, or another conflict.
+                this._log(`Merge: Cancelled ${filename}`, LOG_LEVEL_INFO);
                 return false;
             }
-            // 2. As usual, delete the conflicted revision and if there are no conflicts, write the resolved content to the storage.
-            if (
-                (await this.core.$$resolveConflictByDeletingRev(filename, delRev, "UI Concatenated")) ==
-                MISSING_OR_ERROR
-            ) {
-                this._log(
-                    `Concatenated saved, but cannot delete conflicted revisions: ${filename}, (${displayRev(delRev)})`,
-                    LOG_LEVEL_NOTICE
-                );
+            const testDoc = await this.localDatabase.getDBEntry(filename, { conflicts: true }, false, true, true);
+            if (testDoc === false) {
+                this._log(`Merge: Could not read ${filename} from the local database`, LOG_LEVEL_VERBOSE);
                 return false;
             }
-        } else if (typeof toDelete === "string") {
-            // Select one of the conflicted revision to delete.
-            if (
-                (await this.core.$$resolveConflictByDeletingRev(filename, toDelete, "UI Selected")) == MISSING_OR_ERROR
-            ) {
+            if (!testDoc._conflicts) {
+                this._log(`Merge: Nothing to do ${filename}`, LOG_LEVEL_VERBOSE);
+                return false;
+            }
+            const toDelete = selected;
+            // const toKeep = conflictCheckResult.left.rev != toDelete ? conflictCheckResult.left.rev : conflictCheckResult.right.rev;
+            if (toDelete === LEAVE_TO_SUBSEQUENT) {
+                // Concatenate both conflicted revisions.
+                // Create a new file by concatenating both conflicted revisions.
+                const p = conflictCheckResult.diff.map((e) => e[1]).join("");
+                const delRev = testDoc._conflicts[0];
+                if (!(await this.core.databaseFileAccess.storeContent(filename, p))) {
+                    this._log(`Concatenated content cannot be stored:${filename}`, LOG_LEVEL_NOTICE);
+                    return false;
+                }
+                // 2. As usual, delete the conflicted revision and if there are no conflicts, write the resolved content to the storage.
+                if (
+                    (await this.core.$$resolveConflictByDeletingRev(filename, delRev, "UI Concatenated")) ==
+                    MISSING_OR_ERROR
+                ) {
+                    this._log(
+                        `Concatenated saved, but cannot delete conflicted revisions: ${filename}, (${displayRev(delRev)})`,
+                        LOG_LEVEL_NOTICE
+                    );
+                    return false;
+                }
+            } else if (typeof toDelete === "string") {
+                // Select one of the conflicted revision to delete.
+                if (
+                    (await this.core.$$resolveConflictByDeletingRev(filename, toDelete, "UI Selected")) ==
+                    MISSING_OR_ERROR
+                ) {
+                    this._log(`Merge: Something went wrong: ${filename}, (${toDelete})`, LOG_LEVEL_NOTICE);
+                    return false;
+                }
+            } else {
                 this._log(`Merge: Something went wrong: ${filename}, (${toDelete})`, LOG_LEVEL_NOTICE);
                 return false;
             }
-        } else {
-            this._log(`Merge: Something went wrong: ${filename}, (${toDelete})`, LOG_LEVEL_NOTICE);
+            // In here, some merge has been processed.
+            // So we have to run replication if configured.
+            // TODO: Make this is as a event request
+            if (this.settings.syncAfterMerge && !this.core.$$isSuspended()) {
+                await this.core.$$replicateByEvent();
+            }
+            // And, check it again.
+            await this.core.$$queueConflictCheck(filename);
             return false;
-        }
-        // In here, some merge has been processed.
-        // So we have to run replication if configured.
-        // TODO: Make this is as a event request
-        if (this.settings.syncAfterMerge && !this.core.$$isSuspended()) {
-            await this.core.$$replicateByEvent();
-        }
-        // And, check it again.
-        await this.core.$$queueConflictCheck(filename);
-        return false;
+        });
     }
     async allConflictCheck() {
         while (await this.pickFileForResolve());
diff --git a/src/modules/features/SettingDialogue/settingConstants.ts b/src/modules/features/SettingDialogue/settingConstants.ts
index e2b016c..220d904 100644
--- a/src/modules/features/SettingDialogue/settingConstants.ts
+++ b/src/modules/features/SettingDialogue/settingConstants.ts
@@ -367,7 +367,7 @@ export const SettingInformation: Partial<Record<keyof AllSettings, Configuration
     },
     enableDebugTools: {
         name: "Enable Developers' Debug Tools.",
-        desc: "Requires restart of Obsidian",
+        desc: "While enabled, it causes very performance impact but debugging replication testing and other features will be enabled. Please disable this if you have not read the source code. Requires restart of Obsidian.",
     },
     suppressNotifyHiddenFilesChange: {
         name: "Suppress notification of hidden files change",