If some measure of quality improves to 150 % of its original value in a study from condition A to condition B, would it be most appropriate, in terms of scientific writing (computer science specifically), to describe that as:
a 1.5-fold improvement
a 1.5× improvement
performing 1.5 times better
In general, it's preferable to use the same arithmetic form when discussing relative change in processes of any kind. Consistency shows consideration for the reader. Where I live and translate, the typical writing style tends to like the "x times more than" and the "x-fold" forms mixed with percentages, which is not that easy to interpret as we can see from the discussion here. Percentages not only are more obvious but they also allow comparison with other percentages. So,
Rule #1, use the same form to compare across your entire discussion or report out of consideration for readers.
Rule #2, use percentages in preference to "times more/less than" or "-fold" forms, which are not as precise and require interpretation.