bench atomic factory get

[bitfaster]

Test cache hit perf:

Method	Runtime	Mean	Error	StdDev	Ratio	Code Size	Allocated
ConcurrentDictionary	.NET 6.0	7.464 ns	0.1457 ns	0.1292 ns	1.00	1,523 B	-
FastConcurrentLru	.NET 6.0	10.086 ns	0.0920 ns	0.0768 ns	1.36	2,352 B	-
ConcurrentLru	.NET 6.0	13.762 ns	0.1698 ns	0.1418 ns	1.85	2,378 B	-
AtomicFastLru	.NET 6.0	19.864 ns	0.3901 ns	0.3458 ns	2.66	846 B	-
FastConcurrentTLru	.NET 6.0	25.805 ns	0.2143 ns	0.1789 ns	3.47	2,544 B	-
ConcurrentTLru	.NET 6.0	29.237 ns	0.1691 ns	0.1499 ns	3.92	2,619 B	-
ClassicLru	.NET 6.0	48.410 ns	0.3152 ns	0.2632 ns	6.50	3,041 B	-
RuntimeMemoryCacheGet	.NET 6.0	113.930 ns	0.7662 ns	0.6792 ns	15.27	49 B	32 B
ExtensionsMemoryCacheGet	.NET 6.0	53.693 ns	0.4258 ns	0.3555 ns	7.21	78 B	24 B
ConcurrentDictionary	.NET Framework 4.8	13.788 ns	0.1387 ns	0.1230 ns	1.00	4,207 B	-
FastConcurrentLru	.NET Framework 4.8	14.947 ns	0.3063 ns	0.2715 ns	1.08	15,182 B	-
ConcurrentLru	.NET Framework 4.8	17.265 ns	0.2214 ns	0.1963 ns	1.25	15,212 B	-
AtomicFastLru	.NET Framework 4.8	37.870 ns	0.7494 ns	0.6643 ns	2.75	358 B	-
FastConcurrentTLru	.NET Framework 4.8	45.358 ns	0.3857 ns	0.3419 ns	3.29	15,358 B	-
ConcurrentTLru	.NET Framework 4.8	48.821 ns	0.6934 ns	0.6146 ns	3.54	15,403 B	-
ClassicLru	.NET Framework 4.8	63.516 ns	0.7653 ns	0.6391 ns	4.60	6,945 B	-
RuntimeMemoryCacheGet	.NET Framework 4.8	282.858 ns	1.7724 ns	1.6579 ns	20.51	33 B	32 B
ExtensionsMemoryCacheGet	.NET Framework 4.8	115.978 ns	2.3292 ns	1.8185 ns	8.40	82 B	24 B