4 or 5 years ago I used Pale Moon 64 for playing and it was good then after an update it started to be quite stuttery and i went to Comodo Dragon with very good results. I kept Pale Moon 64 to use with the forums and all other WGT related activities except playing.
Each time Pale Moon 64 updated I would test it always with the same results, the meter was quite stuttery. It updated again today and when I tested it WOW the meter was ultra smooth and very responsive to the clicks. I played 2 rounds with it and not a single stutter.
So if you are looking for a good stable browser to play WGT you might want to try Pale Moon 64 version 27.4.1. I will now set it to never update again.