OS X El Capitan Performance
Apple also focuses on the performance so OS X El Capitan should run faster on your Mac than OS X Yosemite without the need to look for more RAM or upgrade to a new computer.
With Metal apps can use the graphics processor easier and more efficiently which can speed up graphics rendering. This will boost the performance of games and apps.
With OS X 10.11 performance boosts you can expect to launch apps faster, switch apps twice as fast as on OS X Yosemite and the update will let you read email faster when you open Mail and open PDFs and other documents faster in Preview.