Coming back at this- I agree buffer size is part of the equation- the other side if your using TinyGPS is to limit what SoftwareSerial is getting feed–
GpsSerial.print(“$PMTK314,0,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0*28\r\n”);
// turn on only GPRMC and GPGGA ----- TinyGPS only uses these two, all others can be turned off