09239: ironhors: Severe slowdown when many enemies enter the screen

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
09239	Gameplay	Minor	Always	Aug 12, 2025, 20:46	Aug 15, 2025, 16:27

Tester	rcoltrane	View Status	Public	Platform	MAME (Official Binary)
Assigned To		Resolution	Invalid report	OS	Windows 11/10 (64-bit)
Status [?]	Closed			Driver	konami/ironhors.cpp
Version	0.279	Fixed in Version		Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	09239: ironhors: Severe slowdown when many enemies enter the screen
Description	When many enemies enter the screen, during stages or at the end of the stages, the slowdown takes place. It wasn't happening on mame 0.268.
Steps To Reproduce	Play the game until the end of a level, where a lot of enemies enter the screen at the same time. Sometimes the screen gets very busy during the levels, especially if you are playing it at the hardest difficulty level as I do.
Additional Information
Github Commit

Flags
Regression Version	after 0.268
Affected Sets / Systems	ironhors

Attached Files

No.23589 hap Developer Aug 12, 2025, 21:10 edited on: Aug 12, 2025, 21:51	Main CPU clock was lowered here: https://github.com/mamedev/mame/commit/8db3f0a9ed5bae28381c26ad41a9bef8d64493d2 1.536MHz is from PCB measurement and also in schematics (more like, it can be inferred that it's the same as other games with a 005885 chip) edit CPU on PCB is a 2MHz part, so less likely the clock rate is 3MHz here.
No.23590 hap Developer Aug 12, 2025, 22:33 edited on: Aug 12, 2025, 22:34	Slowdowns happen on PCB too, see this video during parts where the game gets very busy.
No.23597 rcoltrane Tester Aug 15, 2025, 16:27	Thank you for the info Hap!