I upgraded from Debian Wheezy 7.9 to Jessie 8.6. I did a complete reinstall from scratch. At the end of the install, I followed the recommendations on page https://wiki.debian.org/NvidiaGraphicsDrivers to recompile the kernel. There was no problem during the install or the compilation.
The machine is an Asus, with a NVIDIA Corporation GK107M [GeForce GTX 660M] (rev a1) graphics card.
Since then, the refresh of the display has slowed down noticeably compared to what it was before.
For the same LaTeX source text file, the re-display of the PDF output of a compilation, which used to be immediate in all cases, now takes quite a bit of time under Okular. The re-display under Evince also used to be immediate, it is also slower now.
My experience with the NVIDIA GK107M [GeForce GTX 660M] graphics card, under Debian Wheezy 7.9 and prior to this upgrade, was that it was a very fast card.
Any help on how to recover at least some of the lost performance would be appreciated. Thanks a lot.