Why interwar anti-submarine development appeared slow

Why was anti-submarine development slow in the 1920s and 1930s?

Development was active, but fleet-wide implementation was deliberately paced to avoid expensive mass adoption of technology that was still changing rapidly.

The Royal Navy continued testing anti-submarine systems throughout the 1920s and 1930s, so the apparent pause was not an absence of technical work. The harder decision was when to install fast-changing equipment across a large fleet. Buying too much of an early ASDIC generation could consume the budget while leaving ships with obsolete sets before war arrived. Gradual peacetime upgrades kept successive generations in use and gave crews experience with the technology. A larger rollout could then follow when war appeared close enough to justify committing to the latest workable equipment.