The resource needs of high energy physics experiments such as CMS at the LHC are expected to grow in terms of the amount of data collected and the computing resources required to process these data. Computing needs in CMS are addressed through the "Global Pool" a vanilla dynamic HTCondor pool created through the glideinWMS software. With over 250k cores, the CMS Global Pool is the biggest HTCondor pool in the world, living at the forefront of HTCondor limits and facing unique challenges. In this contribution, we will give an overview of the Global Pool, focusing on the workflow managers connected to it and the unique HTCondor features used by them. Then, we will describe the monitoring tools developed to make sure the pool works correctly. We will also analyze the efficiency and scalability challenges faced by the CMS experiment. Finally, plans and challenges for the future will be addressed.