So yea... I've spent the last 2 weeks trying to figure out why my woocommerce site (7000 items, with 11,000 comments) was slow.
Such a frustrating experience.
I implemented Redis, Elasticsearch (for faster database queries), upscaled my server to 8GB of Ram + 4 Cores, had over 5 different technicians try to make adjustments to the server.
I went down the route of clustering (having multiple servers) but still no luck.
As it turns out... the issue is in 2 areas:
1. Woocommerce doesn't (Yet) support dedicated tables. Instead it stores everything on a ridiculously slow wp_postmeta table.
They are working on an upgrade to their databases structures, but so far, this will be several months away.
2. The Alidropship Woo plugin is definitely slow during imports. I asked my host to enable up to 4 PHP workers (which is very optimal for high-load servers). The Alidropship woo ended up using ALL workers (whatever that means), thus timing out the server. Alidropship needs to slow-down and limit resource usage while importing (or have a feature that limits resource usage).
3. When enabled, Alidropship can be extremely slow, causing the Time to first byte (TTFB), take 3-5 seconds (which is way above the Google recommended 200ms).
Hence, Alidropship Woo should be experimental, and still under development, rather than part of the ADS releases.
I dropped Alidropship (original ADS) because it's not optimal for setting up a store. It's extremely limited in it's functionality, and doesn't support the huge Woocommerce plugin database (especially bulk editing of certain attributes.
For now, I'll be going back to Shopify (with their bullshit one by one aliexpress import apps).
Alidropship is still FAR superior in its import and cashback capabilities than anything on shopify (atleast anything publicly available), but that's about it.