You would be best off using a format that is more standard. FRAPS can put some weird stuff in an .avi container. Stuff the normal video editing world has no clue about.
Matching your project settings to the media being used will also speed it up. As you showed it Vegas has to convert everything from the weird format FRAPS garbage to the 720×480 project Vegas was set for. This all takes time.
P.S. The lag in putting a file on the timeline was not that long, especially coming from an external hard drive that might not have been spooled up.
P.S.S. You might find people more helpful when not running a pirated copy of Vegas.