I'm writing an application in GWT. It went really well, until I ran it in IE.
I made an application that uses a FlexTable, and each cell of the table was to be highlighted. I wrote the MouseOver handler, but in the Internet Explorer it works incredibly slow.
Is there anything I can do about it?
FlexTable's performance kinda sucks in IE (BTW, which version of GWT are you using?), because of the DOM methods needed there to create the table. However, Grid should provide you with a nice boost in performance, if the size of your table is constant and known beforehand and you don't need jagged tables (otherwise you can't even use it :)).
A compromise between the two would be one of the tables from GWT's Incubator - for example ScrollTable has support for mouseovers straight out of the box and BulkTableRenderers should speed up the creation of your table (there's even a version for FlexTable). Even if you are not interested in using them in production, it might be worth checking out, for example, how they implemented MouseOver events on IE.