Here's an interesting table showing how much resources an application
uses and how much it gives back on shut down.  This is take from
Windows User May 1993 issue:


Application		Min. Resource Use	Resource Not Returned
			GDI	USER		GDI	USER

WinSleuth Gold v3.03	10	6		2	14
Word For Windows v2.0b	10	0		5	0
Lotus 123 v1.1		13	3		3	2
Arts and Leters v3.12	7	7		3	1
PowerPoint v3.0		9	1		3	0
Corel Draw v3.0		10	6		3	0
Micro. Designer v3.1	10	2		2	0
CrossTalk v2.0		0	0		0	0
Excel v4.0a		11	8		0	0
HiJacck v1.0		2	2		0	0
Image-In Color Pro	3	2		0	0
PIcture Publisher v3.1	21	8		0	0	
PowerLeads!-
  Executive Ed. v1.03	0	5		0	0
Adobe Type Manager v2.5	1	0		NA	NA
Skylight v2.0		1	0		0	0

*The numbers are in percentage and are in a decreasing order.

What does this table tells you, if you frequently start and exit a
program that doesn't give back all of it's resources, then you
continually lose these resouces.  Therefore, only open these programs
up once and leave them open.


BTW:  Maybe people can add to this list so we know what application to
watch out for.