Cool to see memcached evolving, a few days ago I had a problem in Redis that was reported to be slow with setting big values in the order of 1 MB, what I did was to profile both memcached (that performed well with the 1 MB payload) and Redis with the same work load, checking with osx Instruments what was the difference in the trace, and this allowed me to easily fix a few problems in Redis (now merged into unstable).

I'll surely check the changes in 1.4.10 as well to see if there is some good idea I can reuse for Redis. The memcached code base is very nice to read.

As entry size grows different parts of the engine are under pressure, allocation-wise and i/o-wise.

AFAIK memcached isn't advised entries above 1 MiB.

We can maintain performance for entries as large as 200 MiB (provided that you have enough memory) but it cost us a lot of sweat!

We haven't benchmarked for larger entries as we weren't sure it would make much sense.

The performances I'm talking for large entries are for our engine "wrpme", not for memcached, I realize it wasn't clear in my post and I can't edit it anymore, sorry about that.

I have read a bit about memcached in the past. I have a lot of video on my site. Would memcached be able to have me specify the most popular videos and cache them so users dont always have to load it? Or is that Varnish?

So many products that seem very similar...

For site videos, if your users are loading them a lot I'd recommend setting far-future expires headers.

But what you probably want in this case is a CDN. Amazon's Cloudfront is easy to set up, but there are many to choose from and they each have their own advantages.

Memcache is used on your server to cache data that you would normally request from the slower main database (probably MySQL).

If you have a lot of video content, investigate a content delivery network. They host your large files in various locations around the world and send them to end users much more quickly than your server can.

I generally use Softlayer's CDN, but Amazon and many others have good offerings.

Memcached is really a bad choice to handle large binary content and by large I mean that 1 MiB is already too much for memcached.

Now how you can speed things up depends on how you stream the videos and at which bitrate.

First try to estimate the size of your "hot" data.