Xbee s1 baud rate 115200 problem

Hi, i have two arduino uno, each one is connected to an arduino wireless shield and xbee s1 plug onto the shield for every one, both also are connected to a pc through usb cable. i successed to make a wireless connection (baud rate 9600) between the two shield and i could be able to read on the serial monitor what is the receiver can received and what the transmitter is send. But my test is simple, for example i sent only some words and switch on and off 2 leds on the receiver side according to to the received words (I using the arduino IDE not the XCTU application). But the problem that when i tried to connect the sender to a robot ( send larger amount data) i received them correctly but slowly, for example i received the updated data after around 1 sec. When i try to connect both arduino again to the PC and change the baud rate to higher one (115200) and even try my simple example to send few words, i can read it correctly on serial terminal of the sender, but on the receiver side i receive garbage symbols ! I searched a lot and i am still confused. But i am not sure if its possible to make the wireless communication with a baud rate higher than 9600 ? Any one have idea about a problem like this !

Thanks in advance