obsstore: cache size computation for fm1 node We have two different types of node type (sha1 and sha256, only sha1 is used now) and therefor different sizes for them. We now compute the value once instead of redoing the computation every loop. This has no visible performance impact.

obsstore: prefetch struct.calcsize This function is widely used and worth but be at module level. No specific performance boost is visible, but this is more consistent.

obsstore: disable garbage collection during initialization (issue4456) Python garbage collection is triggered by container creation. So code that creates a lot of tuples tends to trigger GC a lot. We disable the gc during obsolescence marker parsing and associated initialization. This provides an interesting speedup (25%). Load marker function on my 58758 markers repo: before: 0.468247 seconds after: 0.344362 seconds The benefit is a bit less visible overall. With python2.6 on my system I see: after: 0.60 before: 0.53 The difference is probably explained by the delaying of a costly GC. (but there is still a win). Marking involved tuples, lists and dicts as ignorable by the garbage collector should give us more benefit. But this is another adventure. Thanks goes to Siddharth Agarwal for the lead.

dirstate: use the 'nogc' decorator Now that we have a generic way to disable the gc, we use it. however, we have too use it in a baroque way. See inline comment for details.