I don't find it an issue-regarding websites speed.
It's quite enjoyable.
Docs...different story...
Out of the Box N810 has no Doc/XLS reader/editor.
The good news is you can install EasyDebian (thank you Qole) and you get full bloawn Open Office.
It is slow, but the list of accessible formats makes up for it.

Just do a search on EasyDebian on this forum

Good luck with your decision.