I just installed 4.3 and I'm really surprised how fast is everything and yes, I notice that the new stock browser is a bit slow. Not by much, but it's not near 4.2.2 performance. The tabs are behaving sluggish and the animation is really not smooth. Well, Chrome is doing fine and what a difference in benchmarks! antutu 29720, Vellamo 2483 html 5 and 833 metal. Also the stuttering in Dead Trigger 2 is gone. I think it's a good trade and there will soon be a fix for the stock browser.
HTC TouchHD:ROM Premium V3.5 - 6.5.x 29022-Sense2.5.2021
Xperia ZR - 4.2.2 official ROM changed (because it was a piece of c****) to Samsung S4 GT-I9505 4.3 official ROM