Hey! This took me quite a while to make and, well, here it is!
These batch files (converted to exe) are a charm. How they function is that they place GTA over as a higher priority than apps like skype, steam and so on. After usage, this, of course, will reset your priorities so that it does not cause any conflicts. Features -


Grand Theft Auto V Launcher has over 10 options to choose from! 
Launching GTA V in Offline Mode
San Andreas Running with higher frames
Being able to use more CPU Heavy Mods and not suffer lag
Play GTA V on a low specced PC (i3 Integrated Graphics, for example)


Enjoy!

GTA Vice City and GTA III Versions coming soon, that's if you want to, although I am aware that it most likely isn't needed, but why the heck not? Maybe you wanna max the hell out of vice city!