My Bitcoin Core app (the latest OS X client) is downloading the chain. It has been at the 95% mark for many hours now. It's progressing, but very slowly.
Is this normal?
I would think so, because this is not the first time this happens to me.
As long as blocks continue to download, then all is well.
The Bitcoin client is doing a lot of disk i/o and CPU crunching when verifying each block, so hardware performance will matter. If you have an encrypted filesystem performance issues are exacerbated.
A slight improvement will come when the Bitcoin.org v0.7 client is released. And large improvements will come with the version after when the LevelDB database is used, improving access speed to reading and writing the data and "Ultraprune" is implmented which lessens the amount of storage.
Other solutions include using Simplified Payment Verification clients. Electrum might be a choice for you to consider if your hardware is borderline for operating the full Bitcoin.org client node.