Weka.io develop a software-defined distributed storage system in D with latencies well below a millisecond (over Ethernet). They use the GC in some parts, but avoid it on the hot path as much as possible as it is a simple pause-the-world mark-and-sweep collector.

All in all, the GC isn't as much of an issue for high-performance applications as is sometimes claimed, but all the recent work towards reducing the dependency on it has of course been done for a reason – in performance-critical code, you often don't want any allocations at all (GC or not), and the large jitter due to collections can be a problem in some situations.