Why is Labview 7 VISA so slow?

I have been using the "old" serial read/writes with no trouble but with Labview 7 they don'r work. When I rewrite them to visa style VI's it takes 2 to 3 times as much time to exicute. Is there anyway to still get the "old" style read writes to work or speed up the "new improved VISA" so it isn't so slow?

Thank you for your response.
My specfic applications uses a whileloop to get Data from both; a JC Controls Model model 520 or Model 620 ,and a Molytek chart recorder used as a temperature input.
The program has a 20 step sequence inside the while loop that completes in 6 seconds with no problem using the "old" serial read/write vi.
When I convert the programs to the VISA serial read/write they do not complete reliably in 9 seconds.
The "old" vi's need a 250mS delay in the write sequence to all the data.
The newer VISA version needs 2 to 3 times the delay and then I still get data reads showing up from the last request. I have tried using both syn and asyn in the vi with no apparent diference. The data transfers range from 6 to 26 bytes. (
The 26 bytes VISA vi takes 3 seconds to get all the data. The old vi does it in 250 mS)
I have not tried to benchmark the modules. I will try to do so in the future and post the results. For now I have hade to dump the Labview 7 and go back to the 6.1 version so I can maintain the programs I have running.
Thanks again for your interest. If it would help I could post or E-mail both VI's.

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