I have just installed Opera 10.52 for Windows. It immediately "feels" faster and smoother than the previous 10.x releases - which is pretty amazing, since they were already very fast. I had moved away from Opera a bit on my work system, because it seemed to have occasional problems with our rather convoluted system of security and proxies. That also seems to be fixed in this release, so far it has done everything I wanted with absolutely no problems.
Now if they would just release 10.5x for Linux...!