Only game i know of (and I've played many) that performs better without HT is CSGO. Example of others, GTA5, Farcry 4/5/ND, Ghost Recon WL, Dying Light, Doom 2016 all perform a lot better when i have HT on. HT off, i lose a good 20fps because some of these games (especially FC5, Doom 2016 and GRWL) my ancient cpu is maxed out. Doom was the only game to stutter though as a result of no HT because fps is a lot higher in this game than the rest, pegging my cpu at 100%. HT on, my cpu usage was around mid 80s, no stutters.
Straight 6 core cpus are quickly becoming core challenged so wouldn't bother with them. These days, it's either 6/12 or 8 if going for high frame rates in modern games with everything else going on in these games.
Cpu frame pre-rendering;