HttpContext.Current.Items is too fast to access item, but How?

I wrote simple test

1. add 100 items to [Collection]
2. read 1000000 times from [Collection] randomly

When

• [Collection]==HttpContext.Current.Items it takes 50 ms
• [Collection]==HttpRuntime.Cache it takes 430ms
• [Collection]==HashTable || [Collection]==Dictionaty 170ms

I guess the overhead of HttpRuntime.Cache is sync

I try to change initial capacity of HashTable/Dictionary? but with no success.

Does anyone know what is the reason of this turbo HttpContext.Current.Items? May I create this kind of object to custom cache implementation(of course with sync imply).

The reason cache is sluggish is because it is thread safe - as you guessed.

Underlying type for HttpContext.Current.Items is a plain Hashtable. Perhaps if you put a snippet of your code, I would be able to explain the difference with the 3rd item.