Reduce polling interval of "observer" threads to limit the number update signals.

src/Thread_CPUObserver.cpp

@@ -127,7 +127,7 @@ void CPUObserverThread::observe(void)
 					}
 				}
 			}
-			msleep(1000);
+			msleep(2000);
 		}
 	}
 	else

src/Thread_DiskObserver.cpp

@@ -88,7 +88,7 @@ void DiskObserverThread::observe(void)
 				previousSpace = freeSpace;
 			}
 		}
-		msleep(1000);
+		msleep(2000);
 	}
 }
 

src/Thread_RAMObserver.cpp

@@ -79,7 +79,7 @@ void RAMObserverThread::observe(void)
 				previous = current;
 			}
 		}
-		msleep(1000);
+		msleep(2000);
 	}
 }