Did you take a chance looking into this one? Best Approach to upload large Assets in AEM
Also, What is the version of AEM you are using? If it is 6.3, please take a moment to go through this helpx articles. There are loads of performance improvements went into the 6.3 release. There may not be a single shot suggested solution, but we could certainly accomplish bulk upload using a combination of multiple approaches.
Assets Sizing Guide and AEM Assets