Most aps that you will not be using can be diabled. Be careful with services, however.  Location Services is vital for maps, disable this and the lag gets worse; it makes it unusable.

I use a Galaxy Tab Pro 8.4 with many apps and processes diabled and the lag is there, but is almost unnoticeable. Bought it on ebay, excelent condition, $81.

Hey, Recommend me a Graphic tablet with pen pressure sensitivity. Looking for a tablet with a higher level of tracking speed and better for a professional graphic designer. Moreover, bigger the physical size better the experience will be.  How about New Microsoft Surface Pro [ shops.ae/computers/systems/tablets/q/graphic+tablet/ ]?

I use an iPad, which is great but always found android to be a little smoother, had a go with a friends galaxy tab and thought it worked great