File upload component, loading too slow

Hello guys, I want to upload file to sharepoint across an API I have created, already achieve that but it's too slow.

I use the following build-in file upload component, and when the file is parsed, It execute the sharepoint upload REST APi, where I pass the file cotent as base64string

the problem is the component spend like 15 second to parse a 6MB file, it's too slow. How can I make it faster?

I have tried without parsing the file, the event as when change, but the file was uploaded incomplete

My REST API query:
image
Where I pass the base64string and the name, I think the base64 isn't complete if I don't parse it.