Project Mercury is a tiny portable tool which tries to improve performance when you're running many applications at once.
The program works by automatically increasing the process priority of the active application, which tells Windows to give it a greater share of CPU time, then dropping priority when the application is minimized.
Project Mercury offers various other tweaks which might boost speeds in some situations - disabling Hyper-Threading, Core Parking - but could also slow you down. Most of the options have no documentation, either, so they need to be treated with care.
The program also has a bonus memory cleaner-type feature which frees up RAM when minimizing an application, or on demand. This rarely makes much difference to performance, but you can try it and see.
– Implemented “Excessive mode”.
– Fixed typo “Implanted” to “Implemented”.
Excessive mode monitors for background processes using more that 50% CPU time and lowers their CPU priority to “Below Normal”, thereby reducing the amount of CPU resources they “steal” from the main program.
This feature use a small amount of CPU resources on the monitoring part, so it is advice to only use in cases where the main feature is not enough, to keep operations smooth under heavy multitasking load.
Project Mercury is easy to use and really can improve application performance in multi-tasking situations when CPU usage is high (there will be no difference if it's low).
There are several bonus tweaks which might help in other ways, although a lack of documentation means it's hard to say for sure.
Fortunately, Project Mercury doesn't install drivers, set up services or change your system in any persistent way. If you do have any problems, simply close it down and your PC will instantly be back to normal.