1. There wasn't any significant lag.
ToS never lags more than 7min and usually stays between the 3-4min for updating.
2. You are trying to fit a square peg in a round hole.
The dynamic watchlist is not for you.
It was not created to provide real-time updating for the scalping timeframes.
Workaround: Narrow down your filters. So your scan returns a more manageable number of results.
Review your results directly from the Scan Hacker.
Hit re-scan to your heart's content.
3. If you believe there is an issue with your ToS settings
a.) click on help
b.) click on system
c.) detach the system overview
d.) adjust the size down to one line.
e.) pin it in a handy dandy place
f.) whenever you see a serious degradation in your free memory, click Collect garbage.
4. Overall, as most of the processes run on the TDA servers; your specific setup has minimal effect.
A good internet connection is obviously critical.
Here are the ToS recommended system requirements:
https://usethinkscript.com/threads/thinkorswim-system-requirements.5356/#post-50358