1. A method for delaying memory accesses directed to cache lines associated with transactional execution, comprising: commencing transactional execution of a block of instructions within a thread executing on a processor; receiving a request from a requesting thread to perform a memory access involving a cache line, wherein performing the memory access involves copying the cache line back to the requesting thread; wherein if performing the memory access on the cache line will interfere with the transactional execution and if it is possible to delay the memory access, the method further comprises, storing copy-back information for the cache line to enable the cache line to be copied back to the requesting thread, and performing the memory access and copying the cache line back to the requesting thread at a later time when the memory access will not interfere with the transactional execution.