NewSoftSerial and UART Serial

I would like to receive data using the standard Arduino Serial functions that invoke the UART on pins 0 and 1. While this is going on, I’d be sending data with NewSoftSerial on pins 2 and 3. Now, NewSoftSerial is interrupt-driven… will I lose data from the UART if it arrives while the NewSoftSerial library is sending?

From another thread: “Interrupt service routines should be kept short and fast. If your ISR take more than one character time to execute, then you could lose incoming characters.”

Will this ever be a problem for me?