[nocman]

The only downside to Clozure CL that I found was the fact that it requires SSE2 instruction support from the processor. There are still some processors around that don't support that -- which can be a bummer if you want to use Clozure CL on one of those machines. Unfortunately, one doesn't always have the option of upgrading the hardware to get around that.

I don't think the developers have worked around that, though I have seen some conversation about it in the past. My limited Google searches on the subject today didn't suggest that anything has changed since the last time I looked at it.

Edit:

Oh, duh, I already said all of this about 4 1/2 years ago:

https://news.ycombinator.com/item?id=1804415

Visiting the system requirements page again suggests the limitation still exists:

http://trac.clozure.com/ccl/wiki/SystemRequirements

[orthecreedence]

Another issue I've had is that you can't use 32-bit libraries from a 64-bit image, even with a multilib (in linux or windows). In other words, if your DLLs/SOs are 32bit, you have to use the 32bit CCL executable.

That's not usually a showstopper for me, though.