Can I run an ATtiny84 on a 20MHz clock for improved SoftwareSerial communication?

I've recently been using an HC-05 Bluetooth module with an ATtiny84 at 1MHz. For whatever reason, 1MHz only drops 1-2 characters receiving in SoftwareSerial, while the 8MHz default drops 3-4. If I used an external crystal to boost the clock speed to 20MHz, would it likely receive more accurately?