Change the vb-search from 4 to 3 characters

I was wondering:

Which is the best configuration for the vb-search when we look for good seo?

- vb-own-search with 4 characters
- vb-own-search with 3 characters
- mysql-search with 4 characters
- mysql-search with 3 characters

Thanks!
Marcel

search really has nothing to do with SEO...

Thanks!
But to continue asking on that point ...
which kind of search do you user and why?

mysql full text

here's the pros and cons list:
MySQL Fulltext vs. vB Search Types - vBulletin Community Forum

Thanks a lot!
Enough reasons to go for mqsql fulltext

But a last question:

What is positiv and negativ about changing from 4 to 3 characters?

Many thanks!

you basically double the size of your indexes, which results in slower searching, but allows to search for 3-letter terms

it really depends on what kind of searches your users do...for example, i have a forum where people may search on words like "pie" or something, so i need 3 letter searches available.

I would need them too.
I got space but I don't want to slow it down.
Is the impact on performance that bad?

i can't tell a difference, personally. i would imagine that it would primarily impact performace at search time, with more content to go through, but i also know people expect to wait a few seconds for searches, so i think the tradeoff of making searches more useful would be worth any minor performance impact.