"Throw Redis at it to speed things up"

"Throw Redis at it to speed things up"
On a 2GB box, Redis is another daemon fighting MySQL for RAM. If your cache hit data is small and read-heavy, OPcache + a filesystem cache often beats it with zero memory pressure.
Before adding Redis ask: am I actually I/O bound on cache reads? Usually no.
— enable opcache first (free, huge)
— file cache on tmpfs if you need shared state
Add Redis when you have RAM to spare and real contention, not by default. Try it tonight.