diff --git a/Builder/IISMainHandler/build.txt b/Builder/IISMainHandler/build.txt
index 7237be0..6a8a8c0 100644
--- a/Builder/IISMainHandler/build.txt
+++ b/Builder/IISMainHandler/build.txt
@@ -1 +1 @@
-1971
\ No newline at end of file
+1972
\ No newline at end of file
diff --git a/FLocal.Common/actions/IncrementFieldValue.cs b/FLocal.Common/actions/IncrementFieldValue.cs
index 81c7b9b..71c2e0e 100644
--- a/FLocal.Common/actions/IncrementFieldValue.cs
+++ b/FLocal.Common/actions/IncrementFieldValue.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
+using Web.Core;
 
 namespace FLocal.Common.actions {
 	class IncrementFieldValue : AbstractFieldValue {
@@ -37,10 +38,16 @@ namespace FLocal.Common.actions {
 
 		private readonly Func<string, string> processor;
 
+		private readonly Box<string> resultBox;
+
 		public IncrementFieldValue(Func<string, string> processor) {
 			this.processor = processor;
 		}
 
+		public IncrementFieldValue(Func<string, string> processor, Box<string> resultBox) : this(processor) {
+			this.resultBox = resultBox;
+		}
+
 		public IncrementFieldValue() : this(INCREMENTOR) {
 		}
 
@@ -48,7 +55,11 @@ namespace FLocal.Common.actions {
 			throw new NotSupportedException();
 		}
 		public override string getStringRepresentation(string oldInfo) {
-			return this.processor(oldInfo);
+			var result = this.processor(oldInfo);
+			if(this.resultBox != null) {
+				this.resultBox.value = result;
+			}
+			return result;
 		}
 
 	}
diff --git a/FLocal.Common/dataobjects/Thread.cs b/FLocal.Common/dataobjects/Thread.cs
index bce218e..a8d2c5a 100644
--- a/FLocal.Common/dataobjects/Thread.cs
+++ b/FLocal.Common/dataobjects/Thread.cs
@@ -272,7 +272,8 @@ namespace FLocal.Common.dataobjects {
 			});
 		}
 
-		public int getLastReadId(Account account) {
+		private readonly Dictionary<int, int> lastReadId_cache = new Dictionary<int, int>();
+		private int do_getLastReadId(Account account) {
 			List<string> stringIds = Config.instance.mainConnection.LoadIdsByConditions(
 				ReadMarkerTableSpec.instance,
 				this.getReadmarkerSearchCondition(account),
@@ -282,7 +283,7 @@ namespace FLocal.Common.dataobjects {
 				throw new CriticalException("more than one row");
 			}
 			if(stringIds.Count < 1) {
-				return (this.lastPostId >= FORMALREADMIN) ? 0 : this.lastPostId;
+				return (this.lastPostId >= FORMALREADMIN) ? 0 : FORMALREADMIN;
 			}
 			Dictionary<string, string> data = Config.instance.mainConnection.LoadById(ReadMarkerTableSpec.instance, stringIds[0]);
 			if((data[ReadMarkerTableSpec.FIELD_POSTID] == "") || (data[ReadMarkerTableSpec.FIELD_POSTID] == null)) {
@@ -290,8 +291,28 @@ namespace FLocal.Common.dataobjects {
 			}
 			return int.Parse(data[ReadMarkerTableSpec.FIELD_POSTID]);
 		}
+		public int getLastReadId(Account account) {
+			if(!this.lastReadId_cache.ContainsKey(account.id)) {
+				lock(this.lastReadId_cache) {
+					if(!this.lastReadId_cache.ContainsKey(account.id)) {
+						this.lastReadId_cache[account.id] = this.do_getLastReadId(account);
+					}
+				}
+			}
+			return this.lastReadId_cache[account.id];
+		}
+		private void lastReadId_Reset(Account account, int _lastReadId) {
+			int lastReadId = _lastReadId;
+			lock(this.lastReadId_cache) {
+				if(this.lastReadId_cache.ContainsKey(account.id)) {
+					lastReadId = Math.Max(lastReadId, _lastReadId);
+				}
+				this.lastReadId_cache[account.id] = lastReadId;
+			}
+		}
 
 		public void forceMarkAsRead(Account account, Post maxPost) {
+			var actualLastRead = new Box<string>();
 			ChangeSetUtil.ApplyChanges(
 				new InsertOrUpdateChange(
 					ReadMarkerTableSpec.instance,
@@ -301,14 +322,18 @@ namespace FLocal.Common.dataobjects {
 						{ ReadMarkerTableSpec.FIELD_POSTID, new ScalarFieldValue(maxPost.id.ToString()) },
 					},
 					new Dictionary<string,AbstractFieldValue> {
-						{ ReadMarkerTableSpec.FIELD_POSTID, new IncrementFieldValue(IncrementFieldValue.GREATEST(maxPost.id)) },
+						{ ReadMarkerTableSpec.FIELD_POSTID, new IncrementFieldValue(IncrementFieldValue.GREATEST(maxPost.id), actualLastRead) },
 					},
 					this.getReadmarkerSearchCondition(account)
 				)
 			);
+			int actualLastReadId = 0;
+			int.TryParse(actualLastRead.value, out actualLastReadId);
+			this.lastReadId_Reset(account, actualLastReadId);
 		}
 
 		public void markAsRead(Account account, Post minPost, Post maxPost) {
+			Box<string> actualLastRead = new Box<string>();
 			ChangeSetUtil.ApplyChanges(
 				new InsertOrUpdateChange(
 					ReadMarkerTableSpec.instance,
@@ -368,13 +393,17 @@ namespace FLocal.Common.dataobjects {
 									} else {
 										return maxPost.id.ToString();
 									}
-								}
+								},
+								actualLastRead
 							)
 						}
 					},
 					this.getReadmarkerSearchCondition(account)
 				)
 			);
+			int actualLastReadId = 0;
+			int.TryParse(actualLastRead.value, out actualLastReadId);
+			this.lastReadId_Reset(account, actualLastReadId);
 		}
 
 		internal static KeyValuePair<AbstractChange, IEnumerable<AbstractChange>> getNewPostChanges(Board board, int threadId, Post parentPost, User poster, PostLayer layer, string title, string body, DateTime date, int? forcedPostId) {
diff --git a/Web.Core/Box.cs b/Web.Core/Box.cs
new file mode 100644
index 0000000..b14fe9d
--- /dev/null
+++ b/Web.Core/Box.cs
@@ -0,0 +1,12 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace Web.Core {
+	public class Box<T> {
+
+		public T value;
+
+	}
+}
diff --git a/Web.Core/Web.Core.csproj b/Web.Core/Web.Core.csproj
index 8c5ef31..48fc1b8 100644
--- a/Web.Core/Web.Core.csproj
+++ b/Web.Core/Web.Core.csproj
@@ -45,6 +45,7 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Box.cs" />
     <Compile Include="Cache.cs" />
     <Compile Include="Config.cs" />
     <Compile Include="Counter.cs" />