Allocation rule generates resource hungry partial clear scripts

Summary:

Clear partial - scripts drive most of model runtime

Content (please ensure you mask any confidential information):

Two allocation rules account for 90% of the running time of a model. When I look into the time most of the time is down to 'clear partial' - can anyone tell me what might cause this and if there is any way to control or reduce it.

Version (include the version you are using, if applicable):

26.08.95

Code Snippet (add any code snippets that support your topic, if applicable):