Vegas pro file size explosion - having to use Handbrake currently I am currently screen recording with OBS and then editing the resulting mp4 in vegas pro

Here is what happened last time i screen recorded as an example

35min screen record at 1920*1080 resulted in 260MB
After importing into Vegas and adding intro/outtro and editing mistakes then rendering as the sony mp4 using standard settings, the file came out to be 2.4GB
I then passed it through Handbrake which compressed it back to 375MB

Im obviously doing something wrong but I have no idea where to start my research. Is there settings in vegas that can render better to get it down to what Handbrake can do?
The easy answer is to analyze the resulting files in order to determine what's happening. mediainfo is a multi-platform open source tool that will help you do exactly that. Handbrake is likely using a much lower bitrate by default than Sony Vegas Pro. If I'm not mistaken, the standard settings for SVP are pretty high. You can prove this to yourself with the aforementioned mediainfo tool, and then solve it by adjusting the SVP bitrate settings accordingly.