I'm currently taking IB Physics SL and I never took IGCSE Physics (only took Biology since I just did IGCSE for a year) and I find it quite time-consuming, but not horrible. It's supposed to be the hardest SL science, and one of the hardest SL subjects overall, and will definitely require you putting in more time than would be necessary for Biology for example, and would also require you to be logical and think through things, but it's definitely a good class, and I like it a lot. I've never done Physics before so I'm sure for me it's more difficult than it is for the others in my class - who find it relatively similar to IGCSE, but still quite different since it's definitely more advanced. I've only been taking the class for 6 months now, but it's not TERRIBLE. I got a low 6 on my first-term exam and that was just due to last-minute studying, so I'm aiming for a 7 overall.
Hope this helps! If you like Physics, you'll definitely like the class :] And if you've taken IGCSE Physics and gotten at least an A, it definitely shouldn't be bad at all for you!