After upgrading to versions 4.3 to 4.4.x, I had periodic problems with the ibf_core_output_cache table. Everything worked fine for 2-3 months, then this table began to increase dramatically and the server was terribly slow because of it, because there were many requests to HDD and it did not have time.
I cleaned the table ibf_core_output_cache, started reindexing and everything was fine for a few months again. Then everything again.
This Sunday I upgraded to the new version 4.6.8 (from 4.4.x). Everything updated fine, re-indexing ended yesterday. But now I see that ibf_core_output_cache is growing again, and noticeably faster than before. If in the morning the table took 77 GB, only a few hours later it takes almost 100 GB. So +20 GB in just a few hours!
The site begins to slow down again, CPU load reaches an average of 20-30%. Although usually the average value is 5-10%.
I hoped that in version 4.6.8. they will fix the problem with ibf_core_output_cache, but the problem stays the same.
I use Redis on my server and have it enabled in the settings, but it doesn't help in any way.