linux server sudden slow downs without high load

I have a web server with the following specs: i7-4770K, 32GB RAM, 500GB SSD (1000 Mbit/s connection). The server is dedicated for the server side of an Android dating application. The app has around 15k daily users. The app regularly experiences slow downs to the point where it barely serves any content. The slow down happens suddenly, and I’ve noticed that when the app is fast the load is around 2-3 (top command), and when it becomes extremely slow, the load drops to bellow 1. What could be the issue? I’ve attached screenshots of the top command showing which processes are using the CPU/RAM, etc.. this is the apache config: StartServers 5 MinSpareServers 5 MaxSpareServers 10 ServerLimit 2048 MaxRequestWorkers 1200 MaxConnectionsPerChild 10000 KeepAlive On KeepAliveTimeout 5 MaxKeepAliveRequests 300 Timeout 300 output of some commands during the slow down Command# top Command# sar -q Command# uptime