One is due to how your video card reacts to the game engine. This causes catastrophic framerate drops.
One is due to new lighting effects that have been added recently. This causes a small hit on weaker cards.
One is due to corruption in cache files. This causes a notable performance hit, but is not frequent.
First, the big one:
To solve the number one biggest problem, where your framerate plummets far below what your video card and settings would generally give, you need to prevent your video card from downclocking itself.
First, get MSI Afterburner or an equivalent. Some video cards ship with their own custom software to do what we need, but MSI is a trusted brand that will work across most chipsets and serves as a good "control" to avoid inconsistant behavior.
Second, make a note of your current settings. Save a new profile to mimic your current clockspeeds etc. so if your main clock speed is shown as 900mhz, have your profile at 900mhz. Some users have had better success by adding five megahertz to this value; so in the example above they would instead create a profile at 905mhz. This incredibly minor overclock can coax certain chipsets into a certain tier of performance.
Third, go to profile management, and apply your saved profile to both 2D and 3D modes. Your video card needs to be forced to keep its performance high even if it thinks it detects a 2D scene; we don't want it downclocking itself needlessly, which appears to be the problem with the recent patch.
Don't forget to apply your changes. Optionally, force your fan speed to 100% if you suspect you have a heat related issue. Take a glance at your GPU core temperatures while idle and while playing to see if anything looks off.
The second issue:
Use your video card control panel to disable Ambient Occlusion either globally (for all applications) or for the Mechwarrior Online executable. The framerate savings may be negligible depending on the relative power of your graphics card.
Ambient occlusion settings can be taxing on a system, especially if video card drivers don't efficiently embrace AO. Forest Colony in particular has a lot of overlapping trees and terrain that looks great with AO, but it certainly uses GPU power to get the shading to look right.
The third issue:
Some users apparently have issues with corrupt shader cache files. Not all users have this problem.
Delete those cache files from MechWarrior Online\USER\Shaders
This step does not need to be repeated often, and doing so often will cause slowdown at the start of a map as cache files are rebuilt.
Edited by Chronojam, 30 October 2012 - 01:33 PM.