Is your Galaxy S7 running slow after 11/2018 T-Mobile update? Several days after receiving this update my phone became sluggish to do anything. Simple things like: swiping to answer calls is taking 2-4 seconds, lighting up a screen when the call is incoming is taking also several seconds. The battery life suffers as well - I am losing about 30% of battery every day compared to how it was before. When I look at what is consuming the battery, Android system is the biggest consumer, about 10-20% each day.

Also, the phone started complaining about running out of space even though I had 32Gb SD card that was empty. Going to storage setting shows that out of 32Gb of internal storage I have only about 1-2Gb free and that's after cleaning all of personal data. Most of the consumption is in the system memory. There is no way of seeing what goes into System memory consumption as the stock tools don't show it's contents.

Does anyone else have this problem? Any ideas how to resolve it?
Here is what I just tried to do and it seems to have worked for now. Be careful when doing this as this may lead to the loss of data.

Installed the app "X-plore". Thanks to the developers of this app - a really great tool! The feature to serve the phone's files over HTTP to the desktop PC is a brilliant idea.

It shows most of the system memory contents. I noticed that directory /sdcard/log was bloated: it had way too many files. Seemed like crash dump files that were zipped into ~6Mb packages. There were hundreds of them and they had dates in the names matching the time when the slowness started.

Deleting those files has freed up ~10Gb of space. The phone is running much better.