Limit of rational expression when x goes to plus infinity, on Nokia N900. It takes 8.8 s on Nokia N810. The calculation time on is shown in green, the noncalculated limit in blue and the result in black (with 8 zoom levels). 
On Nokia N810, the definition of derivative of sin(x) using limit when delta goes to 0 is cos(x) as expected. On Nokia N900 it is faster : 3.0 s. Greek characters can be seen with the help of line completion editing of the expression, variable and point fields. 
The
above limit result is pi, calculated using numerical approximation with
500 digits, on Nokia N900. The Nokia N810 runs in 3.9 s.

Limit from the left which is
minus infinity, on Nokia N810. The Nokia N900 runs in 0.02 s.

The menu of "Limit" on Nokia N900. 
There are many settings for "Limit", here the default ones on Nokia N900. "Symplify terms" can take a long time for large results, when it is better to choose "None" or "Expand terms/all". 