Another tip :
I would suggest also looking at your settings though, some of the settings for me atleast was cranked up crazy high, that I know my machine couldnt handle(read my machine is ok, but not top of the line, so I have to tweak some of them).
Example push 200 fps, this I lowered and things improved vastly.
Some of the patch did alter my settings, to "ultra" which I cant run on my specs, dialing it down, I have had no issues in performance in general.
For the question you raise about checking the files ->
Please follow through the steps below to solve your possible crash and not launching problems. Please note that crashes can originate from a number of different sources. They might be related to our end or modification you have installed or can be related to your hardware. Please don't...
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Check this list, and look at the
How to Verify Game Files through Steam