Frequent Lag Spikes and FPS issues

1.7.10 ISSUES:

Experiencing frequent lag spikes every few seconds or when sounds are played, turning sounds off helps but issue is still frequent. This started happening out of nowhere, I did nothing to my PC.

This issue does not however happen on a 32bit OS.

14w29b ISSUES:

Same lag spike issues as above on x64, however on x86 FPS drops to 10-15 when moving around, if I stay in the one spot it goes to normal but when I move it drops again, this happens on all 1.8 snapshots, this doesn't happen on x64 but spikes are the same on that.