\AppData\Roaming\Mp3tag\data\library\mp3tag.db3) is listed in the process explorer's lower pane. Additionally, when I instruct the application to cleanup the library it apparently does so.
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### Author:  [@ohrenkino](https://community.mp3tag.de/u/ohrenkino)
#### Post date: [April 14, 2019, 3:27pm UTC](https://community.mp3tag.de/t/library-not-used-during-startup/45129/4 "2019-04-14T15:27:45Z")
This may be a trivial question, but: have you switched on the library?
Have you set any folders to be included in the library (so that no files outside these folders are added to the library) or no folders so that any loaded files are included.
BTW: if you find that the library is used by MP3tag then the original statement that the library is not used, is at least questionable.
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### Author:  [@Larry](https://community.mp3tag.de/u/Larry)
#### Post date: [April 14, 2019, 3:37pm UTC](https://community.mp3tag.de/t/library-not-used-during-startup/45129/5 "2019-04-14T15:37:46Z")
Most certainly I have switched the library on. I have also switched it off and closed Mp3tag, then switched it on again. I have tried both ways to exclude and to not exclude folders as well.
And by the library not being used I was referring to its original purpose of speeding up the startup process (which it still does not do).
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### Author:  [@poster](https://community.mp3tag.de/u/poster)
#### Post date: [April 14, 2019, 4:04pm UTC](https://community.mp3tag.de/t/library-not-used-during-startup/45129/6 "2019-04-14T16:04:09Z")
> [@Larry](#):
>
> Upon removal of a thrid-party virus checker (and thus reverting to Windows Defender) MP3TAG does not use the library any more after a PC boot.
I have had a similar experience about which I wrote in the german section of the forum:
> [@Mp3tag als 64 bit version](https://community.mp3tag.de/t/mp3tag-als-64-bit-version/13046/85):
>
> Aus der Nähe war es auch nicht so einfach.wink Problem gelöst, das Einlesen klappt wieder innerhalb von 6 Minuten. Ich habe mal in Richtung Virenscanner überlegt und dann festgestellt, dass sich der Windows Defender in den Vordergrund gespielt hatte. Mein installierter Virenscanner ist von Avast und war mit dem Schutzmodul deaktiviert und der Defender war aktiv. Das habe ich rückgängig gemacht und MP3Tag sprintet wieder beim Einlesen. Nachvollziehen kann ich es allerdings nicht wirklich. …
I too had a third-party virus scanner and the defender had accidently been activated without me noticing. Disabling the defender and reactivating the third-party virus -scanner resolved the problem for me.
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### Author:  [@ohrenkino](https://community.mp3tag.de/u/ohrenkino)
#### Post date: [April 14, 2019, 4:24pm UTC](https://community.mp3tag.de/t/library-not-used-during-startup/45129/7 "2019-04-14T16:24:18Z")
AFAIK the original purpose of the library was to cope also with big collections with even more than 100,000 files.
Before the introduction of the library, only some 50,000 files could be treated in one go.
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### Author:  [@Alfatipo](https://community.mp3tag.de/u/Alfatipo)
#### Post date: [June 27, 2020, 4:33pm UTC](https://community.mp3tag.de/t/library-not-used-during-startup/45129/8 "2020-06-27T16:33:36Z")
I can confirm that windows Defender in Win 10 does interfere with the library function.
After adding Avast (Defender disabled) it restored library function (thankfully!)
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### Author:  [@poster](https://community.mp3tag.de/u/poster)
#### Post date: [June 27, 2020, 5:57pm UTC](https://community.mp3tag.de/t/library-not-used-during-startup/45129/9 "2020-06-27T17:57:18Z")
You can use the defender if you define an exception for mp3tag.exe.
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### Author:  [@Alfatipo](https://community.mp3tag.de/u/Alfatipo)
#### Post date: [June 28, 2020, 12:36am UTC](https://community.mp3tag.de/t/library-not-used-during-startup/45129/10 "2020-06-28T00:36:56Z")
Thanks. I'll try that.
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### Author:  [@Larry](https://community.mp3tag.de/u/Larry)
#### Post date: [June 29, 2020, 4:03pm UTC](https://community.mp3tag.de/t/library-not-used-during-startup/45129/11 "2020-06-29T16:03:30Z")
What worked for me after lengthy trials was an exclusion for the process "mp3tag" (without any extensions) in Windows Defender.
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### Author:  [@system](https://community.mp3tag.de/u/system)
#### Post date: [February 9, 2026, 12:28pm UTC](https://community.mp3tag.de/t/library-not-used-during-startup/45129/12 "2026-02-09T12:28:02Z")