Note 4 restarts, severe lags too, why

[frank1492]

My Note 4 occasionally restarts, but worse there can be input freezes of a minute or more. These lags come in flurries, sometimes not occuring for several hours. If a freeze does not resolve by itself in several minutes, a reboot may be necessary. I sometimes get a "process system not responding" notification. Perhaps unrelated, I get full screen popup ads recently.
I have cleared the system cache, and installed a new battery. I do not want to do a system reset.
Any ideas? Help much appreciated. Thanks.

 

[B. Diddy]

The most likely culprit is some app you installed that is also responsible for the adware. The next time you see an ad, use this method to determine which app is responsible: https://forums.androidcentral.com/a.../901497-full-screen-ads-how-find-culprit.html

 

[frank1492]

When my phone runs in safe mode, there are no issues so its obviously an app. Will use your link to try to track it down. Many thanks for your help.

 

[L0n3N1nja]

When my phone runs in safe mode, there are no issues so its obviously an app. Will use your link to try to track it down. Many thanks for your help.

I've got several old Samsung devices including a Note 4 still. I've found clearing the cache/app data on touchwiz home and setting up the home screen again improves performance.

 

[frank1492]

Thanks all for your ideas! Today my phone rebooted and froze while in safe mode, identical to what it did in normal mode!!!! So I am ruling out an app as the culprit. Advice has been given to try to reflash the firmware next, but I do not want to lose any data. Will I? Assuming I do reflash with no effect afterwards, I guess that leaves just a possible hardware issue, meaning a new phone, correct? Again many thanks for helping me.

 

[B. Diddy]

Have you also tried wiping the cache partition? https://support.t-mobile.com/docs/DOC-28932

 

[frank1492]

PROBLEM SOLVED! The SD card was corrupted. Had read some time ago that this could be a possible cause, but I didn't pursue it because to me it seemed unlikely. I was tipped off by a notification that said I needed to reformat the card. All photos& videos were wiped. Apparently tho the card was causing the issues before it finally failed completely as media were accessable until last night. I had wiped the cache btw. Again many thanks for everyone's help!