Optimizing/Improving WHERE

Here's a sample SELECT statement:


SELECT T1.F3
FROM T1 INNER JOIN T2 ON T1.F4 = T2.F4
WHERE
(T1.F1 > @iNum AND T2.F1 > @iNum)
OR
( @iNum2 * (T1.F1 - T2.F1)/(T1.F2 - T2.F2) ) + (T1.F1 - ((T1.F1 - T2.F1)/(T1.F2 - T2.F2) * T1.F2) ) > @INum


As you can see, the second part of the WHERE (after the OR) is much more complicated than the part before the OR. My query would run a lot faster if it tried the first part of the OR and didn't bother with the second part if the first part was satisfied. Is there any way to do this?

Thanks!

Tyler