I’m having the same issue here. eM Client needs about 57 seconds to load. My database with local mail archives is located on another drive. When I move database to C: eM client needs just a few seconds to boot.
This is an obvious bug since there is no real reason why a program would need 10x more time to access data on another drive.
I think it is something that the way Windows Security works with drives other than C.
The only way to fix it is to Exclude the eMClient folder in Virus & threat protection settings > Manage settings > Exclusions.
Performance in eM Client is determined by two things; the read/write speed of the disk and your network infrastructure. So as you moved the database to another disk, it most probably has something to do with the disk. A mechanical hard disk is 100s of times slower with read/write than an SSD. That means when eM Client starts, it will take a lot longer to load the database from a slower disk.
IMHO there is something fundamentally wrong with database file management in eM Client. My whole local database folder is less than 700MB. This size is really not a big deal for modern computers. Copying that whole folder to my C: drive takes less than 2 seconds. Making a copy of the whole folder on the same drive needs less than 10 seconds. So drive speed is not really an issue here.
Do you say that eM Client has to index the whole database file every time it starts and perform R/W operation for every single email separately? What is that for anyway?
Moving files to faster drive is just temporary solution that would just mask a real problem. If my database file grows to 20 GB I’ll have to wait 30 minutes just to start an e-mail client. That’s nowhere even close to acceptable. I’ve been using Thunderbird and The Bat! before and none of these clients had similar problems, even with much larger database files.