Although it's probably frustrating but providing it works is the main thing.
What it may be is due to "possibly" a program that you have installed at some time that is loading in the background but taking a little longer to load and hogging the load sequence until the program has completely loaded.
One of the main problems with this type of problem is possibly not knowing for sure how long it's actually been like this, it may be it's been happening for some time but you have only just noticed it, so it's not easy to pin-point the offending program that may have been installed.
When coming out of standby all the programs have been and are still loaded, so no, the problem should not occur at that point.
What you could try is to disable programs in the start menu, by dragging them out of the start menu (do not delete them) into the normal list of programs, "you can always drag them back later" to see if that helps.
Or, by going into the "System Configuration Utility > Startup" option and again disabling them one-by-one (just remove the tick from the check-box) to see which one may be causing the problem.
You can access this by typing "msconfig" (without the " " ) from the Run option of the Start menu.
Start with the programs that you recognise and would not matter if disabled.