100km/h was slow today

Best speed in 18M class 111 km/h with 500m AGL cloud base in the first cylinder.
Very weak West part of the task then improving to the East and approaching thunderstorm from the West. Because of high speeds in my class each km/h is very expensive. Still hanging in the first 10, but big names just behind me. It looks that 18M class flies faster then open.
Jerzy