Ultra slow Win7-64 guest after deleting snapshots

[Wiz67]

Hi all,
First post and relatively new to VirtualBox so be kind. I have a Guest OS (Win 7 64 bit) running on my Win10 64 bit host. When building this guest I created some snapshots at various stages so I could revert if needed. After successfully running my guest for a few months, I decided to remove the snapshots to save space on my limited SSD. To be clear, my guest was running a flat VDI on an SD card in the host, and the snapshots were by default on the host SSD. This is why I thought deleting them may be a good option to reclaim space there (it would also allow me to move my Guest to the SSD if I chose to). I followed the VirtualBox instructions and began by deleting the first snapshot. During the process it said it was merging the snapshot and would take some time. It did take quite a while but was successful. I then proceeded to delete the second snapshot (also successful) and finally the third snapshot (again, also successful). This left me with my "current state" guest and plenty of reclaimed space on my SSD.

This would have been happy days except that when I went to use my guest next time, it was horribly slow in response. I have read many posts and trolled the net looking for why this would happen. Nothing seemed to apply to my situation. I validated my guest hadn't suddenly been listed as 32 bit, I added more virtual memory, I added more vCPU, made sure all updates were done, etc etc etc. Now I know I will get told that running the VM on an SD card is not a good idea and may be the cause. However, it was working fine prior and was never lagging. I have tested the card and the R/W speed is fine. The lagging is really pronounced and makes the guest practically unusable, waiting minutes for simple windows such as explorer to pop up. When I check both host and guest Task Manager, neither show a CPU or Memory problem.

I really don't want to have to go through and rebuild this Guest again as it is a work SoE build and is very painful (hence the 3 snapshots during build), so I would like to rescue this in VirtualBox if possible. If I have to rebuild I am afraid it will force me to switch to VMWare for this guest so I can get business support for issues like this. I'm hoping someone in this forum can give me practical advice that may help fix this (I have seen other posts which were replied to with "unhelpful" comments). I also upgraded my VirtualBox SW to Version 5.2.16 r123759 (Qt5.6.2) in the hopes that may resolve this.

PS: I know everybody says that deleting a snapshot won't cause this, however the fact remains that this Guest operated fine for months up until these snapshots were deleted, and I have to surmise that this is the root cause 'somehow'. I just need to know if it is recoverable or if it is easier ad quicker to start again.

Cheers,
Wiz67

[mpack]

Please provide a VM log file. With the VM fully shut down, right click it in the GUI. Select "Show Log" and save "VBox.log" (no other file) to a zip file. Attach the zip here.