ArcGIS Server Identify Operations Slow?

Here is a quick tip for my fellow ArcGIS Server developers. While I have never been a big fan of using the Identify operation, there is no doubt that it can be quite useful at times. Its strange though, sometimes I have noticed that it was terribly slow (I have seen 8 sec+ response times on a simple 4 layer Identify). So, I'd do the normal thing, and remove some layers, and try again. It would usually end up being one specific layer that was causing the huge slowdown. I would just chalk it up to a bad layer and move on. Well, after running into this issue a few times, I couldn't really ignore it and blame it on a 'bad layer'. It turns out that these layers had something in common...The all had complex / detailed geometries.

I'm not entirely sure why a complex geometry would effect an identify operation, but it does. So, my simple fix was to use ArcToolbox and perform a generalization operation against the layer. You GIS folks should be familiar with that type of thing. In short, it removes superfluous geometry in the shape. Instead of 1000 points along a curve, it can reduce it to say, 100. Visually, you can normally not tell the difference. But, to be on the safe side, I left the original layer alone, and just made a copy. Then, I use that copy in all all my identify operations instead of the original.

Yes, it does create extra overhead and some additional logic in your app, but the run time processing saving is huge. My 4 sec response times have been cut to under 100 millisecs. Yeah, its that big of a difference. So, in my mind, totally worth the extra effort.