If you want to increase performence then you have to use mainframes because mainframes provide facility as you want.
Mainframe is the technology of new generation develped by IBM only for business purposes.
now a day most of 70% business data is depending on mainframes all major companies are now using mainframes.
so i recommend mainframes for you.
else if you want to reside on less data you can use unix .
unix and mainframes are differ from each other having os and JCl commands etc.