Sometimes the most effective solution is the most obvious one. Reset your Bluetooth headphones and speakers then try reconnecting them again to your computer after a few seconds. With luck, it would reset the laggy connection and improve audio sync. Resetting your headphones removes all previously paired devices.
On my brand new Dell the sound lags by about 0.5- 1 second when using my Bluetooth headset.   This does not happen on my Lenovo, TV, phone etc. There is a problem with the Dell. This is extremely frustrating. Any solutions? 
Laggy sound on bluetooth headphones