Maybe warning is a bit strong, let's say a bit of advise to people that have added the spider hack to their boards.
In the text file with instructions for implementing the spider bait hack you are given a warning about the possible load that it can place on your server during the time your boards are being crawled. This is a serious issue for large boards on shared servers. Another warning warns about impact on your boards if you don't have the accelerator enabled.
Please listen to these warnings. I've helped more than one site troubleshoot problems that ended up being caused by using this hack without enabling the accelerator and being on a shared server. UBB already has a reputation for being a resource hog and a lot of hosting companies no longer allow it as part of their less expensive plans.
We all know that UBB Classic is a great product. The spider bait hack is a must have for anyone that wants their forum content to be searchable. Just remember that it's easier to set your site up properly than it is to have to troubleshoot problems later or find a new host because they booted you for using more than your share of the server resources.
I've also seen cases where the server crashes with a ton of perl processes.
