Using:
Windows XP Service Pack 2 (5.1.2600)
Windows Live Messenger 8.5.1018
Messenger Plus! Live 4.60.0.324

Whenever a toast from msgplus is supposed to be delayed, it shows about 5-10 seconds later than when its supposed to.
I was configuring a local copy of YASS, and I was getting a connection error to the database, which displays a toast on error.
the toast was probably 10 seconds late in displaying. Immediately after hiding, WLM's toast for media playing is shown (even though I had music playing before signing in).

EDIT: just forced a toast again, having the debug window open. The trace message that is supposed to display the same time as the toast, actually has closer to 30 seconds between them.

EDIT2: Also unrelated, why isn't there a context menu for copy, paste etc. on the debug window?

Can you try restarting your computer? it seems that Messenger Plus! may be timing out waiting for another application to display its own popup.

I have done so, but its still happening

Are you using several Messenger (polygamy) or any other addon? also, does it happen for any Plus! notifs? (from scripts, custom notifications, etc...)

No, I am not using polygamy, or any addon except Plus. and it is ONLY happening for Plus notifications, all toast messages from Plus (scripts, contact online/offline, etc), but any WLM toasts are being delayed as well it seems if there's a Plus toast waiting.

i have noticed this as well, but about 2-3 second delay

I don't know if it's related, but I noticed this too with mail notifications, the first toast (lower on screen) does not appear until the other ones (which are displayed "on top" of the invisible first) disappear...

well, Plus! notifications do not mix with Messenger notifications, that's was done for clarity and reliability reasons. Is this what we are talking about?

WLM's toasts are not a problem for me, just Plus!'s ones

i'm using the same stuff as you but the toasts aren't delayed.

this is happening for me =S

it is really annoying because toasts take ages to load

well, there must be a reason.... when you say "ages", is that about 30 seconds too? is that everytime, for any event and any script? can you confirm that reinstalling Plus! 4.50 fixed the problem?

Today it seems to have been working OK for me, and I haven't changed anything except for deleting all the registry keys for WLM after it refused to start for me (happens occasionally, don't know why. Process shows, but nothing happens. Deleting reg keys allows it to start normally)