1. A method of processing data operations comprising: receiving, from a requester, a read request for first data at a data storage system; determining whether the read request results in a cache hit whereby the first data is stored in a cache of the data storage system, or whether the read request otherwise results in a cache miss; and if the read request results in a cache miss, determining whether to perform cacheless read processing or deferred caching processing to service the read request, wherein said determining whether to perform cacheless read processing or deferred caching processing is performed in accordance with criteria specifying that a percentage of read requests resulting in a cache miss are processed using the cacheless read processing and that a remaining percentage of read requests resulting in a cache miss are processed using the deferred caching processing, said percentage varying in accordance with a measurement indicating a level of busyness of a back-end component used to retrieve from physical storage any portion of the first data not currently stored in the cache.