I'm running Minecraft on the following machine: Windows 8 x64, 8 GB RAM (4 allocated for Minecraft), i5-2500K @ 4.5Ghz, AMD Radeon R9 290.
I've got about 70 mods including Buildcraft, Thermal Expansion, and some other common technology mods. I haven't had this issue in earlier versions of Minecraft. As for Forge, I'm using 1226 (one of the latest builds).
Now when I play independent of which map and with or without mods, the game is running very patchy. I get an average framerate of 30 with Mods and ~60 without Mods. Though I have at least 30 FPS, the game stutters. This is caused by random lag spikes which occur all 1-10 ticks. Here a screenshot of my lag-o-meter and the profiler:
Like you can see, a lot of irregular spikes and very high tick times. Moreover, in Debug view I get every now and again a message that something is taking too long and "root" or "root.tick" or "root.render" or others took approx. 110ms.
Now as I'm curious I tested the same on a machine that is set up exactly the same but running on an Intel Celeron (2-cores) @ 3.2 GHz and with an Nvidia Geforce GTX 560 Ti.
The game runs perfectly smooth with all mods. The ticks are short and equal and I get an average of 60 FPS with Mods and highest viewing distance. Here take a look, the same world just on the other machine:
You clearly see the difference and the profiler shows that the ratio between Tick and Rendering is exactly the opposite to mine here.
Now does anybody know why this happens to be? I really don't get it. I've tried out all. Various Java parameters people suggested all over the web, tried Java 8, tried different Java versions, played around with the allocated RAM but nothing helped... It just doesn't run smooth and playing so is horrible.
I recently had a problem that randomly the menu's lagged and audio glitches (CPU frozen) occurred in Thief. Since that time I went down with the clock, though a lot of intense burn-ins said it would be stable. Now, these glitches didn't appear anymore, but I can't believe that Minecraft stresses the CPU so much that it's getting unstable... Moreover, I tried Terasology (maximum graphics settings) when the clock was still higher. It ran with a smooth 60 FPS and without issues. I tried it again a few days later and then it lagged the same as Minecraft did, just that Terasology sooner or later crashed with a "somewhat Delay" exception. I guess the same issue — unstable ticks.
All other games work just fine, without any troubles. It looks like it's just with Java games...