I've been running my test websites (WordPress) on my QNAP, but loading the pages could take 15 - 20 seconds (TS 869, Intel) which is just ridiculous. So after some digging I found that the caching by default was not enabled in Apache.
To enable this, you'll need to login to your QNAP with SSH and type the following:
After the line that load the PHP module (LoadModule php5_module modules/libphp5.so) add the following line:
LoadModule cache_module modules/mod_cache.so
Close Nano (CTRL+X, Yes, press ENTER) and restarts Apache:
/usr/local/apache/bin/apachectl -k restart
If that doesn't work well, do it in two steps:
/usr/local/apache/bin/apachectl -k stop
/usr/local/apache/bin/apachectl -k start
And your webserver will be faster ... (takes about 2 seconds to load a page after that on my QNAP)
Note: If you have a slow QNAP with limited memory, then this might not work. In such a case you might want to look into LoadModule disk_cache_module (modules/mod_disk_cache.so), where Apache caches on disk instead of memory (see also: this Apache document).