I keep seeing sporadic performance on the server of mine, and I am discovering it difficult to identify/repair the problem. Typically, pages load rapidly, but 10-20% of times they load very gradually. In Chrome's network tab shows "waiting" time as 99% from the lag. I have even examined loading an empty PHP page which has no output and that i still begin to see the wait time get large on 10-20% of page sights.

I have attempted timing the PHP script which is consistently have less all page sights, including those that have lengthy wait occasions. For instance, I possibly could load the blank page and it'll load in 150ms, after which I load it again also it loads in 8500ms, but both occasions the PHP script performed in <.5ms.

Any applying for grants what else might be leading to this (I have examined on multiple computer systems/systems and am getting reviews from customers from around the globe)?

With internet servers you will find a lot of areas that induce difficulties with load occasions. I've had similar results with one website I manage. Using the internet, it composes of multiple areas. The programOrequipment on your pc, your router, your Web service provider gateway, the road it requires to get at your hosting, the gateway of the hosting, and also the software/hardware in your server. Each one of these may cause bottlenecks based on current load. The most typical reason of waiting time may be the research or saved routing table. Here's your computer systems arp and network cache and may be removed to ascertain if it corrects (it has assisted in some instances). Rather than looking to get the quickest route it uses old pathways which might are in possession of high loads.

Second is that the server might be have less assets. This is often more true if you're on hosting that is shared. For those who have a devoted server, I'd look at your resource usage if this appears to become slow. There might be a procedure that's hogging the assets at certain occasions, example is really a cron job.

Without checking these there's not a way to be aware what the problem is. The only real factor I'm able to have to say is to check on all you can and run tracerouts/pings to determine the server occasions and also the path you're using.

Connection issues/packet loss

Can it be a higher packet loss in your connection? TCP connections sometimes achieve timeouts where there's packet loss, whereby it misses an association initially, however (in worst situation) handles for connecting after a little seconds price of retrying.

Obviously, you'd notice issues not only viewing your website, but any web site on that connection.

Contention around the server

Could it be a shared server, and may other clients on a single server be utilising a lot of IO or CPU, or active Apache processes, sometimes?

You'd debug this using the top command (to determine general CPU usage or load queue) or even the ps -AH v command (to determine the amount of active Apache processes and an introduction to another processes running too).