This sounds like exactly the kind of thing I'd waste a weekend setting up but what do you actually do with the decrypted traffic? What do you inject? I know you said it's personal but maybe some basic ideas.

Do you find any websites or services that fail because of cert pinning or similar? Why do you restrict dns caching to periodic intervals, just for external privacy?

In terms of the speed I doubt the time to decrypt and encrypt tls is noticeable in modern times, especially given how slow websites have become. It's not like a load balanced website behind cloudflare isn't already doing this 3 times