I've just recently updated to 1.8, and am experiencing a bit less fps than promised what with all of the supposed optimizations made. Normally, in vanilla minecraft on, 1.7.10, on far render distance (16 chunks) i would get around ~250, or if my computer is feeling really good, ~350fps. (specs below). With the recent 1.8 update, on far render distance, i only get around 100fps, and if i set it to extreme (32 chunks) render distance, i only get 24-30 fps. If anyone knows how to solve this performance problem, it would be greatly appreciated.
Well, to start, Minecraft is not optimized, whatsoever. With that aside, when similar things happen to me, (assuming you have a up to date java installation) I uninstall java COMPLETELY, restart my PC then goto the java SE download page, and download the 64 bit java and install it, then i restart my PC again, and run minecraft. A fresh java install fixed many issues for me.
I'm getting the exact same problem. I have a Gaming PC, and I average 60-90 fps with vsync off and VBOS on. One of my friends doesn't even have a graphics card and gets around 1000fps in minecraft 1.8. I have an AMDfx-8320 and an AMD R9 270x running Windows 8.1.
[PC SPECS]
GPU: nvidia GTX 780 (zotac branding) (most recent stable drivers)
RAM: 8GB (4GB allocated) @1866MHz
HDD: 1TB 7200RPM
OS: Windows 8.1 (most recent update)
Go here for the 64 bit java 7: http://www.oracle.com/technetwork/java/javase/downloads/jre7-downloads-1880261.html
Thank if I helped
Open minecraft, click edit profile, check JVM Arguments and type: -Xmx500M -Xms500M, if this is not working try changing it to -Xmx1000M -Xms1000M