4
I will take a look at the Xoopstool...
As regards speed, excepting a little extra code to load where the block is shown, there should be no degradation. There is definetly no DB impact. The only thing I can think of is aspells processor usage, which should not be much.
BTW - This module requires aspell and php compiled with aspell support. This was no issue for me, on my Gentoo Linux box. But your mileage may vary.
JMass