Performance of eM Client on SSD versus Hard Drive

I am running eM Client on 3 computers - an old 2010 MacBook Pro, which is stuck on eM Client 8.x, an iMac 27 2017 (9.2) and a Windows 11 laptop (also on 9.2). I also use a local IMAP server for manual filing of important mails, and take advantage of the automatic archiving feature on the iMac in order to keep storage down on my various Gmail accounts.

Now, here is where my question(s) come in. The iMac, which has a decent Core i7 and 24GB of RAM, is the SLOWEST of all for launching eM Client. It literally takes about 5 minutes to start eM Client, or to close eM Client. The other two computers are much much faster - like an order of magnitude faster, coming up in a few seconds. The two laptops both run from SSD storage. Now, granted, they don’t have the local archives that the iMac has, but the other thing is - the iMac is the last computer I have with a spinning hard drive - it has what Apple calls a “Fusion” drive, which is a 1TB 7200rpm drive with 32GB of SSD storage that caches the most frequently used data. Never had any performance complaints with Apple Mail or much of anything else on this computer, aside from eM Client.

Oh - and SEARCH in eM Client on the main computer (iMac) is agonizingly slow…

I am wondering if my performance issues are due to use of a traditional hard drive versus an SSD, or if its is due to the large volumes of locally archived email.

I do have an external USB-C connected SSD that always stays attached, and have toyed with moving my eM Client Database directory and Backup directory to a folder on that device.


  1. Does anyone thing moving storage to an SSD is the answer to my performance issues?

  2. To move the database directory, the FAQ and manual indicate that if you change that folder, you must manually move the data in order to avoid eM Client creating a new empty database. Do I change the setting (creating an empty database) and then move the data to that location, or move the data, then startup eM Client (won’t find its data?) and change the setting?

Any guidance or advice is appreciated.

Moving to an internal SSD will definitely improve loading the database because the read/write speeds are 100s of time faster than mechanical disks. eM Client’s performance is also almost completely dependent on database read/write throughput, so there will be improvement there as well.

But if it is an external drive, while we don’t really recommend that, you can give it a go and see if there is any difference. The disk itself may be faster than the mechanical disk, but its use really depends on the USB port speed. Not just the specified speed of the port, but if you have two devices on the same USB channel, they are limited to the speed of slowest device.

I would also be concerned about the connection to the disk being lost for some reason, and causing data corruption. But if it is reliable, all you can do is try and see what the result is.

To move the database, change the location in Preferences > General > Storage. Then quit eM Client and move the /Users/yourusername/Library/Application Support/eM Client/ folder contents to the new location.


Thanks. Unfortunately, I won’t be attempting to open up the iMac to put an internal SSD in until the internal hard drive fails. It’s a lot of hassle in this model, and involves detaching the glass from the front side, to get into it, then putting it back with adhesive strips once done, and there is some risk I break the 27" 5K panel in doing so. Used to be a local non-Apple Mac service place that would have done it for me, but COVID put them out of business.

The external 1TB SSD is the only thing on one of the Thunderbolt 3 ports, so when I said USB, I guess that was only partially true. The drive itself is USB-C, but the port is Thunderbolt, and it is connected using a 1 foot USB-C cable. I’ve yet to see it drop the connection in a couple of years of use. It benchmarks as about 15x faster than the internal drive for read/write speed, despite being external.

So I think I will give it a try, using your advice on moving the data. If performance still is sluggish, I’ll move it back.


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