From SA-MP Wiki
SA:MP has limits for many things. Below is a table of the most common limits that are in SA:MP. Note the 'text I/O' value - that is for the text that is sent to the client, and that is used on OnPlayerCommandText.
As new versions are released, limits change, and some old versions' limits have been preserved for comparison, or if you are still using old versions.
|Vehicle Models||Unlimited **||127|
|Global 3D Labels||1024||N/A|
|Per-player 3D Text Labels||1024||N/A|
|Chat Bubble String||144 characters||N/A|
|Attached player objects||10||N/A|
|Text I/O||128 cells (512 bytes)||128 cells (512 bytes)|
|Name Length (SetPlayerName)||24 characters||16 characters|
|String Length||1024 characters||256 characters|
|Shown In A Single Client's Screen||92||92|
|Created Serverwise (Global)||2048||1024|
|Created Serverwise (Per-Player)||256||N/A|
- (*) There is an optional 800 player slot version (since SA-MP 0.3d R2) and a 1000 player version (since 0.3e) available.
- (**) Although the vehicle model limit in 0.3 is unlimited, if you use a large amount of vehicle models, you may notice parts of your mode become framey as vehicle models are dynamically loaded/unloaded. Keeping the number of vehicle models below 150 is a good idea.