Lawn Bowls is a Target Sport like Archery; so try a Slow, Controlled, Back Swing in the Delivery

There is no correlation between how rapidly you take your bowl back in the backswing and how much forward-directed force is provided to your delivery. No matter how rapidly you draw it back, the bowl becomes motionless at the top of the pendulum swing. Therefore, whatever velocity the bowl is intended to have must arise from the acceleration from both the forward swing and forward body motion. Rapidly drawing your bowl back has no advantage.

Nonetheless, drawing your bowl back quickly has disadvantages.  First, your bowl is less likely to remain directly above the backward extension of your aim line and as a consequence your bowl will not pass through your stare point on the aim line when you swing your arm forward.  Second, if proper elevation is part of the means by which you control length, the accuracy of your delivery weight will be reduced.

So your lawn bowling backswing should be performed with the same care as an archer draws his bow.