Rakudo needs better performance from Parrot, and Parrot can provide it. Here are several areas of exploration.

In progress?	Explanation	Difficulty	Amount of Work	Benefit Estimate
*	FixingConstantSTRINGCaching	moderate	low	big memory savings, 3% performance improvement, further benefits from other string changes (avl_string_cache branch)
*	RemoveUnnecessaryDataFromConfig_lib.pbc	low	low to moderate	5-10% Parrot startup (2.926% achieved with r45623, more possibilities await)
	String equality macro	low	low	2-3%
	Slim parrot_string_t	low	low to moderate	2-3%, depending on workload
	Make fast core the default core	low to moderate	low	2-3%(done in r46436, is there any other work to be done?)
	FixingPIRVtableOverrides	moderate	low to moderate	5%
	Fix freeze/thaw of complex PMCs	difficult	moderate to high	huge startup improvement for Rakudo
	Implement sweep-free GC	moderate to high	moderate	10%, depending on workload
	Remove PMCProxy	high	moderate	5-7%
	Implement garbage-first GC	high	high	10-15%
	Type-specific hashes	low to moderate	low to moderate	3-5%
	Store CallSignatures in PBC	moderate	low to moderate	7-8%
	Cheaper access to object attributes	moderate to high	moderate	5-7%
	Lorito	high	high	orders of magnitude

Completed tasks:

Remove PMC struct's sync

low

low

2% at most (done in rr46289)