I usually use "at the cost of", but my editor made it "at the expense of". For example, the following sentence:
The counts in Table 2 are all based on implementations that are optimized for computational cost, which comes at the cost of significantly increased storage costs in ...
was replaced by
The counts in Table 2 are all based on implementations that are optimized for computational cost, which comes at the expense of significantly increased storage costs in ...
Can anyone help explain the difference?