Testcase with 500 requests: Okhttp3 1st: Heap size peak: 142Mb Threads peak: 19 Executed time: 177s Okhttp 2nd: Heap size peak: 160Mb Threads peak: 20 Executed time: 132s Vertx-web-client 1st: Heap size peak: 237Mb Threads peak: 14 Executed time: 91s Vertx-web-client 2nd: Heap size peak: 252Mb Threads peak: 14 Executed time: 104s