Why stopping services? Aren't my specs are good enough to handle them all?
Although you might have decent CPU, tons of RAM or even with SSD drive. However, these services are fighting each other to get processor resources and many of them relies on fixed hardware connections which have limited capacity to make solid performance. Stopping services will minimize work-load of svchost controllers, freeing more resources for allocation and improve system responsiveness. If stopping services sounds little too scary, you can skip this process as it's not the most important features after all.
It seems some features like stopping services are missing in this version. Are you trying to reduce features?
From what I've seen in concepts, I thought it should be 100% safe for any machine to use it. However, stopping most system services can cause unexpected problems in some machines. I got reports about Fidelizer breaking some applications and services, heavily slow down system because of recent updates in 1.2, etc. So I decided to take them off to ensure this program will 100% safe for yourself. However, I added something new that can be very effective in return and no one ever make it this far before too.
What does Fidelizer do in optimizing threads, I/O and random stuff like priorities and resources scheduling? Are they just made up for placebo effects?
Since Windows Vista, Microsoft introduced Multimedia Class Scheduler for thread and I/O priority optimization for processor resource scheduling. Most dedicated audio/video applications will benefit from this and it also affect overall system/network performance too. Default configuration are quite terribly optimized and not enough people going to take this feature serious enough to findout how I can get better sound through this. Fidelizer will do it for you without affecting real configuration so everything will still work fine after system restart.
I saw system thread priorities and clock resolution in another option. Aren't they the same to ones in resource scheduler?
Although Microsoft made pretty good resource management tool like that. However, it couldn't controll the whole system down to specific process and thread. This program will do additional works to ensure best sound reproduction with lowest possible latency in software and hardware I/O which can loosen up the continuity of bit-stream though it's performing bit-perfect. It'll enforce audio thread to highest level possible and reduce non-important processes and threads to lowest possible level for more throughput to audio thread. It also adjusts system clock resolution (NT Timer) down to lowest possible level for most accurate timing reference to improve stability of audio playback at lower latency.
I use DPC Latency Checker but Fidelizer doesn't improve system latency at all. Isn't it scam?
Graph in system latency shows latency of hardware I/O meaning you're checking hardware latency. Fidelizer will decrease software latency in operating system so DPC Latency Checker isn't capable of checking software latency. You need to test it with other methods. If you want to decrease hardware latency in DPC Latency Checker, try disabling drivers like networking for example.
If DPC Latency Checker is out of the game, how can I measure the difference in scientific way then?
You'd need high quality hardware and intensive measurement methods to make clear cut. Let's just believe in Microsoft that they didn't make stuff like Multimedia Class Scheduler just to fool pro audio market. If you're really desperate to do so, just try it with your ears, if you're unsatisfied or can't hear the difference, just delete it since it won't cause any changes to your system anyway.