How to make [attach] bbcode always show as inline image

[Andy]

When using the [ attach] bbcode in a post it shows as an inline image. But if it is copied to another post it only shows as a link.

I would like to modify the code so that the [ attach] code will always show as an inline image.

[Brad]

It is done like this because showing it in posts it isn't attached to would cause a hit in preformance. There are of course work arounds but they are not simple to do and require time to get right.

[Andy]

I was able to accomplish this, it works great and there is no noticeable speed degradation.

[mavherzog]

I was able to accomplish this, it works great and there is no noticeable speed degradation.
How?