[stumped]

1. take out the SD card and re-test. some kindles don't play nicely with some SD cards

2. if no improvement then try the various reset options: before resorting to factory reset try the "hold down power button for 40 secs until it shuts itself down" one. that one preserved your apps, but does more than a simple restart.

3. the only other erason I can think of for slow running is that a rougue app or process has gotten on their - like a crypro coin miner - that is runnign in the background and stealing power. I think its pretty easy to find the list of " running apps" on a KF and check: settings, apps, select running apps column , check for anythign unexpected.

4. clear cache on all the browser apps may also help - the KF may be running low on storage. some caches grow & grow until tamed. ditto for news apps, and check for auto download of news stories in the news apps settings which can also hog bandwidth and storage. settings apps choose an app, clear cache, repeat...

5. if you are intending a factory reset, check first that you have backup ( to amazon) enabled) and force a backup. that way you will see a "restore from" option to quickly get your apps and settings back after re-registering, though you will lose any passwords...