When like the problem occurs, try to isolate the problem as follows.
1. Isolate the problem if it depends on the browser.
Check if the problem occurs on the Firefox/Chrome. It is possible to verify if the problem is the problem depends on the browser. When IE is used, check if your IE version is supported version.
We have received the topic like the above on IE earlier version is used from the customers. Especially, the performance of the IE8 and IE9 was very slow by their architecture. It is not only SDM but also the other application. As IE earlier version is not certified and not supported, we cannot mention anything about the behavior when you use the IE earlier version. Before opening the case, check the behavior on the supported IE version and Firefox/Chrome. Firefox/Chrome are better performance than IE.
2. If the problem occurs on all browser, try to remove the customization and check if the problem still occurs.
3. If the problem still occurs, take the fiddler trace with reproducing the problem. The TEC485575 explains how to use the Fiddler.
4. If the fiddler trace does not notice you anything, contact CA Support with the fiddler trace.