I've been running PH for several years, and have never seen PH cause the problems you are talking about woob. If you are getting such low performance, what process is using the CPU? I.e. do you see PH using 100% of 1 cpu? FWIW, cpu usage on many cpu monitors running on windows doesn't show the classic definition of cpu usage, so seeing a process that is using 100% of a cpu isn't easy.
Normally, before multi-cpu+multi-cores, you saw (100*cputime/realtime)% as the value of
%cpu. This definition was kept on OS's where you could have 100's of cpus (sgi unix, cray unix). On OS's where it was more important to hide real cpu usage from users, the cpu usage is give as a %of time spent in cpu vs. available cpu, where available is always 100 whether you have 1 or 1000 cpu's. This gets even more difficult when you start using cycle based percentages or start getting fractional parts of a cpu (like in a virtual machine.). The only way to find out if a program is using alot of cpu is to multiple the cpu% you see by the number of cores in your system (if you have hypercores, enabled, it will be twice the real cores, but you won't see twice the cpu power). So if you have 6 CPU's with hyperthreading enabled, a process using 8.6% cpu, is really using 100% of 1 core. If you have hyperthreading enabled, you'll never really see 100% cpu usage, because the hyperthreads aren't real cpu's (they share hardware with another cpu).
Also, if you want the fastest single-threaded performance (or if you are worried about the speculative execution security bugs), you'd be best advised to turn hyperthreading off. Since most programs can't use parallel execution, they don't really benefit from hyperthreading (though some programs can, most don't), and even when they use parallel execution, they aren't doing the same thing, so you don't really benefit as hyperthreading was intended to use multiple threads running the same program.
In any even, you need to find out what program(programs) are causing your slow down, since PH shouldn't be doing that. It's possible some malware is causing the problem by doing busy wait-spins when you run PH in order to keep you from running PH regularly and being more likely to detect malware as it is executing.
I hope you find the problem. I'm curious as to what would be causing it.