Done Game constantly freezing and FPS lagging after playing longer time

My game starts freezing and lagging very often after some time playing (more than 1 hour, but it is random).

After fresh start of game, it doesn't lag and everything is fine but then after long time it starts lagging. I don't know what is causing the lag. I don't have any resource intensive stuff running except minecraft.
I am using Optifine and Fastcraft too.

Can someone help me?

 

I don't see any graph after pressing f3.

But the used memory rapidly increases and then go down.

 

Is your memory usage really high when you check task manager? Ctrl + shift + esc is the shortcut on windows.

 

Yes, it is. I have 98-99% physical memory used.

 

Yeah you got a memory leak then [DOUBLEPOST=1456418885][/DOUBLEPOST]Im guessing none of the programs are using a high amount of memory?

 

No, they aren't using big amount of memory, all other programs (counting system processes) are using under 100 mb together.

 

Can you go to this directory and run a program called poolmon. C:\Program Files (x86)\Windows Kits\10\Tools\x64[DOUBLEPOST=1456419280][/DOUBLEPOST]Might need the windows kit.

 

Should I run it while minecraft is running?

 

Can you close minecraft. Your mem usable will probably be high still. About 60%.[DOUBLEPOST=1456419553][/DOUBLEPOST]Unless it is minecraft ofc.

 

From what I remember, I had after startup of computer around 50% memory used (I saw it in task manager).

 

hmm, that's rather high after a computer start up. Normally restarting the PC clears the mem cache. I'd probably disable some of the start up programs to reduce that.

 

I have only torrent and microsoft security essentials on startup. That amount of memory used I have even after 20 minutes of using computer (No minecraft, no normal programs running).

 

This is the post I used to help me find the Nonpaged kernal memory. Windows 10 high memory usage (unknown reason) - Super User[DOUBLEPOST=1456420568][/DOUBLEPOST]This helped me detect what the memory leak was and google a bit to find a fix.[DOUBLEPOST=1456420602][/DOUBLEPOST]This also might help. Troubleshooting Nonpaged and Paged Pool Errors in Windows

 

Ok, I will try it.

 

I know, I said the observation in my first reply. I was just a bit confused.[DOUBLEPOST=1456431158,1456422427][/DOUBLEPOST]I rebooted computer and checked poolmon and task manager. Oddly, nothing is using big amount of memory in poolmon and same it is in task manager (I counted that it is less than 1 GB), but still I have more than 1 GB of ram used (I have 4 in computer).

 

Rebooting the computer will clear the memory cache. This makes it much harder to find the memory leak. You need to look for the leak when it is happening.

 

The problem is that the leak is happening very significantly only when I play minecraft. Should I start the modpack up and then use poolmon?

 

If it is only present when Minecraft is running then yes run the application [DOUBLEPOST=1456431575][/DOUBLEPOST]Possibly re-installing the pack/updating java should help.[DOUBLEPOST=1456432610,1456431547][/DOUBLEPOST]How much memory are you allocating to minecraft?