Video freezing with certain subs enabled

There is an odd video freezing that happens once in each of the episodes for this series but only when the integrated subs are enabled. When disabled there is no video freeze, nor when using "3." subtitles (for ep 01) or "6." (for ep 03), either locally or integrated.

For EP 01 it happens about 10 seconds after Part A starts, around the 5:30 mark.
For EP 03 it happens right at the beginning of the episode.

There are rips from two different groups, using different subs. You'll notice the freezing from the DB group is longer and more pronounced than the second group's. I swapped the subtitles, and the freezing behavior follows the subs, not the video encode. Again, no video freezing/stuttering when subs are disabled or when using the separately uploaded subs.

I have 17.6.6 Mega installed. I watch 4K and HDR videos all the time, some with subtitles. No issues encountered except this.

Link to videos and subs:
https://drive.google.com/drive/folders/1ZuL5isTKoreU5xF1jUx5PeQy-_qMrZxS?usp=sharing

Adding some additional observation: the freezing/stuttering only happens one time per episode exactly when the translation for the episode title is coming on screen. The sub's font and placement for the episode titles are different than the rest of the text, special. That has to be the key to what is causing this.

F.Y.I.
I updated to 17.6.7 and the issue is unchanged.

I am not getting any freeze.

With Process Monitor you might be able to figure out what is being done that causes the delay. For example, in the past there used to be an issue where loading "atmfd.dll" (a font related file from Windows) could cause delays.

https://learn.microsoft.com/en-us/sysinternals/downloads/procmon

I think I figured it out. In the Subtitles menu, my max texture resolution was set to full 4K. Changing it to 1080p stopped the freezing from happening at those episode titles points.

Higher texture res requires more processing power.

I'm sure, but that setting has been set at 4K res for a couple of years without issue. Watched lots of programs with subtitles. So, there is something special happening with these. Plus, aside from my GPU, I have a superpowered system, 5900X, 32GB, 1TB 970 EVO Plus, and a 1060 3GB (with latest drivers). Could the subtitles really be straining my GPU because of texture size?

Subtitle rendering runs on the CPU.

I did not have any issues with those files on my much older CPU. But I don't have a 4K screen. The subtitle doesn't have any complex animations, so I don't know why you are getting problems.