what kind of apps can cause high I/O?

The problem is high IO, mainly read 50 to 150 MB/s (shows always as 100% tho), for about one minute of despair, lowering the quality of the android realm user experience. The only way to know for sure, would be https://www.xda-developers.com/check-io-usage-iotop-android/amp/ So, i would need root and a specially compiled kernel (rom?). But, if you could hint me, mainly if yours have an iotop like app, it could be enough. Android 6.0.1 I tried stopping gallery, i thought it was scanning media, didnt help. During high IO, i saw zygote, /system/bin/installd, system_server use a bit cpu but on top of the list, but that is a proccess, not an app (that we could stop). I use simple system monitor app. And i need to know HINTs of the app/proccess, not the overall IO neither what specific proccess here is causing trouble (as hints may suffice), so I can try stopping them by chance. Thats why my question differs from: https://android.stackexchange.com/questions/132659/view-disk-utilization-activity (also the accepted answer there doesnt answer about showing specific proccess IO, that is in the body of the question, therefore the accepted is just a partial answer).