Welcome to the forums!
There will always be a bottleneck somewhere in your system, and what it is varies based on the specific task you are working on.
While your CPU is not a top-end enthusiast level component, it is more than sufficient for most tasks.
As such, it may offer an occasional bottleneck, but the upgrade to an RX 480 over your IGP is still very much worthwhile.
My recommendation? Get it and start enjoying it!
-outlw