Usually, lsws out of box settings should be OK.
General guideline is:
1. make sure to build matching php if lsws reads apache httpd.conf.
2. check WaitQ column in real-time stats. If it is zero all the time, then no system delay on php process (good thing). If stays non-zero, you need to increase PHP suEXEC max connections.
3. follow guide to enable LSWS cache (for dynamic page like PHP) as point out earlier. you should see cache hit rate in real-time stats if working.
4. run 'top -c' see which process consume most cpu cycle.