I agree with Steve completely. It’s either the file or something you’ve done. In this case, I have a suspicion it’s the latter since I have no problem with your file. I did a test render this morning and it looks the same as the original. Your rendered version, the slow one, appears that you have changed the playback rate to something less than one. Go to your clip on the timeline, right-click, and select properties. It should look like this.

You can reduce the playback rate to .25 and it will give you a slow motion effect. However, to see the entire video you must do a ctrl-drag to the right as far as it will go.
If you want normal playback, like the original, just make sure both the playback rate and undersample rate are set to 1.0.
One question. Are you designing your videos mainly for YouTube distribution? Both the original and rendered files have a frame rate of only 30 fps. At best, YouTube supports 60 fps. If that’s the case, there is absolutely no reason to capture at such high frame rates. (600 fps or even 120 fps). Captures matching your delivery frame rate should be the best. The quality of each frame will be the highest and it will put less burden on your system. Such high frame rates would be useful if you intend to produce “slow-motion” versions of your action sequence.
wwaag