Not really the case. There all sorts of optimizations in place (row caching, Bloom filters) that give adequate read performance. Is the read performance suitab

Not really the case. There all sorts of optimizations in place (row caching, Bloom filters) that give adequate read performance. Is the read performance suitable for the OP, given his workload, his hardware (i.e., the amount of RAM he can give to Cassandra, the speed of his disks)? I don't know, but the only way to find out is experimentally.