I usually have a very good startup time with my H140 (that's my impression when I compare it to the startup-time survey conducted here at MisticRiver), because I often do the "folders first trick" and sort my files/folders in alphabetical order and have my collection of complete albums perfectly tagged. I usually have a startup time of:
previous startup time without DB: 9.7 sec.
previous startup time with DB: 1:28 min.
But today I achieved an
improvement of
62.5%!
my new startup times are:
new startup time without DB: 10.0 sec. (because I loaded in more files since last test)
new startup time with DB:
33 sec.! 
The size of my collection is:
4194 songs (mainly 192kpbs MP3 + some Ogg Q7 albums)
0575 folders
24 GB Music / 14 GB data (the data is in 3x4GB+1.5GB PGP-disk to avoid folders and fragmentation between data and music files. I have positioned the PGPs at the back of the disk)
It is already well-known that the number of folders have effect on the time spend on HDD-reading at startup, because all folders have to be scanned. Collecting the folders in the front of the HDD will improve this compared to the case where the folders are scattered all over the HDD. This trick will also effect the startup time without DB enabled. It is probably also a good idea to avoid fregmenting the "iRivNavi.iDB"-file because this file is read in at startup when DB-Scan is enabled.
So what was the trick? :P
... you ask
Well... this is completely new to me and I have not had time to investigate the exact reasons, but I can tell you that I did three things differently yesterday when I did the "folders first trick" with "xcopy" (the command prompt program).
My theory is that the structuring and sorting of the TAGs in lists are performed on startup when the DB is enabled. I especially have the "TITLE"-list under suspicion for being quite time-consuming to sort/structure.
The first thing I did different was that I had to convert all my TAG title from "##-title"->"title" without converting to filename first. So I used the MP3BookHelper suggested by "alienrider" (EDIT2: I have later on come to the conclusion that it should avoided to have the ##-title syntax in the TAG title field). While doing this conversion I selected that the new TAGs should be ID3v2.3 and I converted & removed some of my ID3v1 -> ID3v2.3.
Afterwards I used "xcopy" to make the "folders first trick" by first coying the folder structure by "xcopy . E: /T" (standing in my H140-backup dir - where E: is my H140-drev) and afterwards copied the musicfiles by "xcopy * E: /S".
(credits go to ep0ch for the xcopy trick) (This should however not be the cause of the improved DB startup time because the resulting harddisk-layout was approximately the same as I achieved with another "folders first trick".) I verified with OO defrag that the file/folder layout in the clusters was acceptable.
Then I used Ewan's new TDT (3.0) to create my DB file. I don't know if he did any improvements in the construction of the DB file, but it is not mentioned in the TDT history so I don't think that is the reason neither.
So my guess is that the consistency of the TAG structure is of great importance for the startup time (I don't hope that's old news
). But maybe you guys and girls can find an even better explaination in the relationship between the TAG structures and DB startup time....
******************* NOTICE ******************
I know that this trick is not very specific yet, but I
hope that we through this thread, with your help,
can specify the trick to more concrete advices on
how to achieve better DB startup time. If we are
succesful in achieving that, the trick can be added
to the FAQ & "Tips & Trick"-thread.
******************** ******************** *****
You can use this http://www.cashcowmag.com/percentage_calc.html calculator to calculate your improvement..
If you receive positive improvements by using the DB advice and the "folder first trick" then post what things things you did and your collection info in terms of number of songs, folders and size. If possible, try to the describe the state of the collection in terms of structuring difference (i.e. I organized my collection from 48 genres into 28 genres and...etc.). Remember to time your DB startup-time before you start to optimize your collection and save a backup of the old "iRivNavi.iDB" file. Time from you press play until the player is ready and showing xxxx Songs, xxxx Folders.