Will I have a downgrade in test speed with TCC?

Generally no. If you see the delays - check the Connection submenu to verify the latency.

Generally, with fast internet, tests should be on par or faster than with the local Docker Desktop. If you notice the test speed downgrade - check the Connection submenu of the Testcontainers Cloud Desktop app, it will show the last captured latency. Ideally the connection latency should be below 20ms.

Also, with TCC, you can run tests in parallel, and, with the Turbo Mode enabled, you can have each test fork connected to its own VM, so you can literally run tests 3-4 times faster.