Using one of my thunderbolt ports (10Gbps) on my iMac i7 late 2013 to connect to a USB C powered hub in order to enhance the speed on my SSD Drives

The miniDisplayPort/Thunderbolt 1 ports on your iMac do not support any kind of USB connection. The adapter(s) won't change that limitation.

The reason the USB-C to Thunderbolt adapter works with USB is because the USB-C ports on more recent Macs support both Thunderbolt & USB. Your 2013 iMac's TB1 ports support only TB1 & miniDisplayPort.

Thunderbolt 3 has a USB 3.1 alt mode and is compatible with USB-C devices.

Thunderbolt 1 does not and is not compatible with USB devices. To make it work you would need a Thunderbolt Dock to provide PCIe to USB protocol translation and NOT a simple cheap USB Hub.

In summery:

1. A Thunderbolt Dock with USB 3.1 ports.
2. An Apple Thunderbolt 1/2 to Thunderbolt 3 cable to connect to the dock.
3. Connect the SSD to the dock.

OWC (macsales.com) sells a bundle with both 1 and 2 for $220.

They also sell used 27" 5K iMacs with native Thunderbolt3/USB-C ports starting at $350.

I would not recommend spending half the price of a new(er) iMac on a hub just to get a single 10GB/s USB port.

I agree with rkaufmann87 in that you should be considering upgrading your computer to a current Silicon model, particularly if you're using your iMac in your livelihood.

The 2013 iMac is considered obsolete by Apple and you'll have trouble getting any parts and service for it. Both will be more costly than that model is worth.

Consider the Mac Mini M4. You can get it with 16 GB of RAM and 1 TB of storage for $1086. It'll blow the 2013 out of the water speed wise. You can get up to 32 GB of RAM and up to 4 TB storage.

Match that with a 27" or 32" 4K monitor w/speakers for less than $350 and it makes an economical package.

Note: if you have a number of external SSDs to connect to your hub I would not go with a bus-powered hub, but one with it's own power.

Just some food for thought.

With anything speed is going to be equal to (at best) whatever the weakest component is. That means if your cables, hub, computer, SSD enclosure, or the SSD itself is the slowest component that is going to be your bottleneck and limit your overall speed. You need to study the speed stated by the manufacturer of each component and whatever is the slowest will tell you the maximum speed you going to get.

IMHO, when you use old equipment at some point you have determine if its time to bite the bullet and begin upgrading.

What external SSD's do you have and how are you using them...?

The 2013 iMac's Thunderbolt/Mini DisplayPort 10Gbps only relates to Thunderbolt and Mini DisplayPort devices.

So on that note: I'm against dumping money into an adapter, a hub and cables for the old iMac.

I would live with the USB 3 5Gbps speed and focus my time and money on getting a new Mac.

The Thunderbolt 1 ports on your iMac do not carry USB protocol.

To use a Thunderbolt 1 port to attach a USB device, I believe that you would need to use an Apple Thunderbolt 3-to-2 adapter to connect a Thunderbolt 3 (not 4 or 5) dock that had its own power supply, and that had a USB port. The dock would need to be wall-powered as the adapter does not carry power from one side to the other.

It would also need to be a Thunderbolt dock, not a much less expensive USB-C hub.

I do not make any guarantees as to whether downstream Thunderbolt ports would carry a USB-C (USB) signal, or what speed you might get out of a dedicated USB-A (USB only) or USB-C (USB only) port.

Your Late 2013 iMac has four USB-A (USB 3.0) ports that run at up to 5 Gbps and that don't cost anything extra. I would suggest learning to live with 5 Gbps speed until such time as you can upgrade to a newer Mac that supports faster, more modern interfaces.

What speed does your SSD support? It would have to be an NVMe SSD, right? As the "normal" SATA SSDs don't go to that USB3.2 speed anyway.