Slow VPS Performance

[hakkuo23]

I've spent hundreds of hours tweaking it, ive moved the mysql db to an ssd, I'm running on nginx using extremely aggresive caching rules, and I get a relatively high pagerank and yslow rating, but other websites with lower ranks load significantly faster! I'm pulling my hair out!

And for the past 6 months I've had a fluctuating performance where it's faster some days while others it's slow as a sin, and it has no pattern behind it, nor is it more present during hours of high traffic.

It's extremely aggravating when another site that has far more content, a significantly lower pagespeed score, and is using apache, loads significantly faster then your site running nginx tweaked to the bone.

wat do?

[Edge100x]

This is more about slow website performance than slow VDS performance. There are a million things it could be, but some of the most common are a MySQL problems such as database not being properly optimized/indexed or being queried in a manner involving slow queries; attacks from 3rd parties hammering at the site (this is particularly common with forums); running out of memory or webserver processes; improperly cached resources (such as running PHP without APC, etc); and packet loss due to routing problems to individual clients.

You should start by looking at your webserver logs to see what's being requested and by whom, and to see if errors are showing in relation to running out of threads/processes; looking at your system logs to see if you're running out of memory; looking at "top", "mytop", and "iotop" to see what processes on the system are using the most resources and whether they're waiting for I/O; examining the APC configuration, if you're running PHP; and running long-term "mtr" commands to and from your client to check for loss.

We run all of our sites on VDSes, as do tons of our customers and internet users on the whole, so the problem definitely is very unlikely to be stemming from the virtualization component .