Case : when either dragging in 6mb un-analysed MP3 to session or arrange, or importing via the enter key (select a track and then select an MP3, then press return - to import the MP3). Also when previewing an MP3 in Live 8.1.5
in any of these cases the application freezes, GUI drawing stops and the application is unrsponsive for at least 10 seconds

Comparative testing Results:
Live 8.1.1 Works fine
time taken to analyse and then drop always less than 1.5 seconds, times range between 0.5 seconds and 2 second. The "no drop" mouse icon shows, but at least it's only for a second. GUI is fully responsive during this time.
Live 8.1.5 Barely works
time taken to analyse, and then drop ranges between 8 seconds and 16 seconds, although most usual on my 10 6 mb tests was a 10 second wait time.
If this is a drag action the (/) "no drop" mouse icon shows for that time
during this time the application is frozen to interaction, Window Title bar reads "Live 8 - (not responding)" with no further GUI drawing at all - meaning all Live menus, tracks instruments and title-bars are in pale grey with no text and unresponsive.
Previewing
the same happens when I select an MP3 to preview , the 'headphones' are active, and an un-analysed mp3 selected. Pressing the right arrow, or simply selecting an unanalysed MP3 starts preview
In Live 8.1.5 the application locks up for ten seconds. Windows title bar reads "Live 8 - (Not responding)"
The Picture shows the situation.
I will track back through the previous Live versions to see when this occurred.
I have 8.1.1, 8.1.3 , 8.1.4 and 8.1.5 installed
8.1.1 is fine, 8.1.5 is terrible
I will report back