Update the OS, this is useful if you're using a particularly old OS and they've made performance improvements, especially ones that impact newer apps.
Remove unneeded applications, if you have a wide array of apps installed on your tablet, then consider removing the ones that you don't use anymore or could live without.
Clear the cache in your browser completely, this should help improve performance issues on boot as well as with your browsing time.
Turn off all of your notifications, this prevents all of your apps from sending you updates on your screen and will help to reduce the intial load on your tablet.
Turn off all location services, for the same reason as above.
Turn off indexing on your tablet, this could slow down a little bit when you open a file that you've not opened in awhile, but it should definitely give you a performance boost on startup.
Consider disabling multitasking gestures if you don't use them as they use additional processing power.