A code review for a smallish change shouldn't take more time than sending a few chat messages. You send them the code review, they look through the 20 lines in the code review tool, note that the changes corresponds to the change description, see that you added tests for it and that those tests passed, they ask you to clarify a variable name, you update the code and send it again a few minutes later, they review the new change and see that the name was properly changed and tests still pass and press accept.
This is how most of the code reviews went for me at Google. If you do a bigger change it will take more time, but I see no reason why smaller should take longer than that. After all you are just sending small bits of text back and forth, it really isn't more complicated than a few chat messages.
The delay isn't always around the review itself taking long. It's having a dev working on their own tickets and then having an opportunity to check in and review someone elses code. You could end up getting a review on your code in 10 minutes or 5 hours based on what's going on for everyone at the time you open the PR. It might even take until the next day and for a bigger PR it could involve a few more eyeballs and time commitment for the review itself (outliers but they do happen).
This is how most of the code reviews went for me at Google. If you do a bigger change it will take more time, but I see no reason why smaller should take longer than that. After all you are just sending small bits of text back and forth, it really isn't more complicated than a few chat messages.