The present invention relates to a processing unit for executing instructions in a computer system and to a method in such a processing unit. According to the present invention a decision is made whether or not to base execution on a value prediction (P), wherein the decision is based on information associated with the estimated time gain of execution based on a correct prediction. According to an embodiment of the present invention the decision regarding whether or not to execute speculatively is based on information regarding whether a cache hit or a cache miss is detected in connection with a load instruction. In an alternative embodiment of the present invention the decision is based on information regarding the dependency depth of the load instruction, i.e. the number of instructions that are dependent on the load.