Time To First Byte (TTFB) is unstable
I’ve deployed my site on a droplet.
All seems fine, I have TTFB ~80ms, which is great for me.
I use caching with simple “file” driver, so cache data is stored in the files on FS.
I’ve noticed that with time (probably when there is no FS activity, about an hour maybe), TTFB goes down to ~500ms (on the same page, with the same cache).
If I flush all the application cache, TTFB goes back to ~80ms.
Is it the normal behavior?
Should I use Redis for cache?