Why are attached files so slow to download from zoho email?

Why are attached files so slow to download from zoho email?

Hi, I am using zoho email since 1 month and i have no issues with text emails, however when they got an attached file it is so frustrating to get the attached file. It takes like 4 minutes to download a 2MG file. I already checked my internet speed and it is 30Mbps, not that bat to get stuck.