Depending on the Size of your AD and what field you are searching on it may take while to return the data.
Getting the info from your Process Manager will likely be faster as SQL searches are usually quicker than AD searches.
For faster results in AD searching you should try to narrow down the OU being searched. The more narrow the search, the faster the results. If you do not have that info, AD has to search the entire tree to find the data you are looking for.
So how many user objects are in your AD? and what criteria are you searching on?
It also just occured to me that I had a similar issue searching one of our external domains, but that domain controller was behind a firewall and not all the AD ports were open. Once the rule was updated, searches came back within seconds. IIRC, it usually took 30 to 40 seconds for the request to be processed. We did a Wireshark capture to diagnose the problem and it turned out to be related to DNS and AD ports...
rob