05931: janshin: Slowdown when the game uses a wavy line effect

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
05931	Speed	Minor	Always	May 3, 2015, 16:54	May 6, 2015, 01:15

Tester	izius	View Status	Public	Platform	MAME (Official Binary)
Assigned To		Resolution	No change required	OS	Windows XP
Status [?]	Closed			Driver	neogeo/neogeo.cpp
Version	0.161	Fixed in Version		Build	Normal
		Fixed in Git Commit		Github Pull Request #

Summary	05931: janshin: Slowdown when the game uses a wavy line effect
Description	There is a major slowdown when the game uses a wavy line effect. This happens twice in the whole game, after the 1st dungeon and by the end of the 1st world map. It's possible that more games in the driver use that effect and have slowdowns as well.
Steps To Reproduce	Load the provided save states, taken just before that wavy effect is triggered.
Additional Information	If your system is recent enough, you may not notice any slowdowns at all. In any case, by pressing the Fast Forward key (default INS), you should notice a performance drop when that effect is used. One last note, I had to use the winning hand cheat to progress that far in the game. I also tried a fair play until the 2nd town, and still had the slowdown problem when that effect was displayed. I don't think the cheat could affect it.
Github Commit

Flags
Regression Version
Affected Sets / Systems	janshin

Attached Files	janshin.zip (508,719 bytes) May 3, 2015, 16:54 Uploaded by izius

No.11645 Tafoid Administrator May 4, 2015, 16:02	If there is nothing wrong with the effect, a simple performance drop cannot be considered alone as an emulation bug. There are a lot of games/driver in which certain effects will bog things down and will be noticeable on lower end systems. Has it always done this or did the effect used to be performed without noticeable impact?
No.11648 izius Tester May 5, 2015, 21:22	I don't know if the effect is displayed correctly - that enemy/UFO is fully visible every other frame, while it's supposed to be still appearing. But maybe it's done on purpose to show a flickering effect, or it's displayed this way because the driver uses partial updates. Anyway, I tested a few older versions, after finding the rollback roms, and it performed OK in the past. The slowdowns began in 0.116u1.
No.11649 Haze Senior Tester May 5, 2015, 21:56	there's always going to be some performance cost in these situations, it can't be considered a bug.
No.11650 Tafoid Administrator May 6, 2015, 01:14	I'll have to side with Haze here. Some functions take processor to do. Perhaps it can be sped up somehow but it is not a priority nor can it be considered an emulation bug strictly due to the increased demands. Closing