I am also having the same issue, but it didn't show up until I installed 8.1. I am having the problem on my new Asus laptop and things were great until I upgraded. I have gone through forum after forum to try to correct the problem and nothing seems to
work. Most programs that use their own fonts don't seem to have the problem, it's only the programs that use the Windows 8 font to render.
Please Microsoft, fix this problem because it drives me nuts!!!
Asus G75 laptop
Nvidia Geforce GTX 660M
1920x1080 Res
Win 8.1 fully updted
If it is new to you for 8.1 and not in IE but in several other programs, than I guess it is the new feature to use different DPI scalings per displays to support connecting different displays with different DPIs.
All application which say that they are not dpiAware (in a manifest resource in their exe-file) get blurry when not shown at 100% scaling which is 96dpi IIRC.
For non-Windows apps you can open the properties dialog of the exe in on the compatibility tab you can check "Disable display scaling on high DPI settings".
For built in apps like Event Viewer (MMC) you can try to patch the manifest resource to set dpiAware to true, but that will break the signature of signed exe files, so running microsoft tools like event viewer (MMC) will come up with UAC prompts for unsigned
apps which otherwise would not happen for correctly signed exe files.
An easier "global" way is to open the display settings (desktop > right click > Screen resolution : Click on "Make text and other items larger or smaller". Check "Let me choose one scaling level for all my displays". That seems to trigger a different behaviour
that programs (at the least the programs that I use) are not scaled up automatically.
HTH
SvenC