I've got the latest version. Plug-in is removed. (Every time I update MC11, it re-installs Audioscrobbler, and every time, I uninstall it... I guess I have to go in and delete some files manually.) I had also turned off several virtual drives a while ago too.
I was hoping that the difference in behavior between Media Library and Playing Now would be a clue as to what was going on...
I'm just rating songs and editing artist and title fields.
I have a relatively large library, about 33,000 files, but I know others have much larger libraries without a problem.
A possible factor is that I have part of my library on a networked drive; it's sometimes connected, sometimes not. But the tag changes are all to files stored locally. Perhaps MC is trying to connect to the network drive every time for some reason? But the problem occurred whether the drive was connected or not...
...
I just created a new library comprising one folder on a local drive, and tagging is refreshingly quick. I'll see if I can import the rest of my local files into the new library without reintroducing the tagging delay again.
Media Center Registered 11.0.148 -- C:\Program Files\J River\Media Center 11\
Microsoft Windows XP 5.1 Service Pack 2 (Build 2600)
Intel Pentium 4 1793 MHz MMX / Memory: Total - 523 MB, Free - 73 MB
Internet Explorer: 6.0.2900.2180 / ComCtl32.dll: 5.82 (xpsp_sp2_rtm.040803-2158) / Shlwapi.dll: 6.00.2900.2180 (xpsp_sp2_rtm.040803-2158) / Shell32.dll: 6.00.2900.2180 (xpsp_sp2_rtm.040803-2158) / wnaspi32.dll: 4.60 (1021) , ASPI for Win32 (95/NT) DLL, Copyright © 1989-1999 Adaptec, Inc. / Aspi32.sys: 4.60 (1021)
Ripping / Drive E: TDK DVDRW880N Mode:Normal Type:Auto Speed:Max
Digital playback: Yes / Use YADB: Yes / Get cover art: No / Calc replay gain: Yes / Copy volume: 32767
Eject after ripping: Yes / Play sound after ripping: No
Burning / Drive E: TDK DVDRW880N Addr: 1:0:0 Speed:8 MaxSpeed:32 BurnProof:Yes
Test mode: No / Eject after writing: Yes / Direct decoding: Yes / Write CD-Text: Yes
Use playback settings: No / Normalization: None