Several machines process items in an arbitrary order (e.g. furnaces do iron → gold → iridum → quartz → copper). That makes automation less predictable for players, and the current implementation has a significant performance impact (since each machine scans all connected chests multiple times).

Process items in the order they're found in chests instead.

Discussed in the forums and Nexus comments.

Done in the upcoming Automate 1.6.