Ask HN: Rails App takes 800ms to respond on a VPS. Will dedicated server help? | Hacker News Reader

Ask HN: Rails App takes 800ms to respond on a VPS. Will dedicated server help?

7 pointsjotto4 comments

I get very little traffic, this is purely a Rails performance problem. I am using New Relic and it's reporting the problem in ActionView. I know it's not a query issue because my queries are all properly indexed and no table has more than a couple hundred rows.

Even if I use some fragment caching, I'm still getting about 300-400ms delay. New Relic is reporting that ActionView is taking the most time. I also render a partial (which renders its own sub partial with AJAX forms) for each object displayed on the page (20 objects per page).

I'm using Passenger and Ruby 1.8.7 EE (just came out within past 2 weeks).

I have also tried booting up a new VPS instance to verify it wasn't the box I was on.

Is it worth trying a dedicated machine or will I see very little performance difference?

The largest difference in performance between a VPS and a dedicated box is Disk I/O (much better on the dedicated).

Given that, I think it's unlikely that just switching to a dedicated box would help significantly.

A useful baseline might be to use YSlow to compare how long it takes to load your page in Rails vs. a static version of the same.

It doesn't sound like the problem is a VPS or specifically a Rails problem. 800ms is a lot, and 300-400ms for a view with fragment caching is a lot. I have a completely unoptimized app in development with 20-item paginated lists of partials containing partials running on a VPS (linode) that renders the uncached view in 130ms. And this is with Haml, which is slower than erb, especially for nested partials.

I don't know what could cause the slow-down off the top of my head. Are there slow helpers? Also, IIRC, iterating over a collection to render each partial is slower than using render :partial => @collection.

Run it on your workstation and see how fast it is. You should get comparable speed from a dedicated server.

Not a bad suggestion, just make sure you're running it in production locally.

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