  This paper introduces a new approach to improve the performance of the
Capacitated Vehicle Routing Problem with Time Windows (CVRPTW) solvers for a
high number of nodes. It proposes to cluster nodes together using
Recursive-DBSCAN - an algorithm that recursively applies DBSCAN until clusters
below the preset maximum number of nodes are obtained. That approach leads to
61% decrease in runtimes of the CVRPTW solver as benchmarked against Google
Optimization Tools, while the difference of total distance and number of
vehicles used by found solutions is below 7%. The improvement of runtimes with
the Recursive-DBSCAN method is because of splitting the node-set into
constituent clusters, which limits the number of solutions checked by the
solver, consequently reducing the runtime. The proposed method consumes less
memory and is able to find solutions for problems up to 5000 nodes, while the
baseline Google Optimisation Tools solves problems up to 2000 nodes.
