Bridge Slow Process Picture from Internal Hard Drive, But Faster When Process Pictures from External

Hi all,

I have issues with my Macbook Air M1 since purchased it on February this year.
I have tonnes of images and i usually doing sorting and move the pictures to folders.

I do found out that when i do the works through internal harddrive of my Macbook Air M1, the performance is so bad. I need to wait long time (very long actually) for all the pictures shows in thumbnail, categorize by date etc. I harddly labelled and rating the pictures smoothly.

Compared to when i connect the Macbook Air M1 with external harddrive and i do all works through it (i processed the pictures from external hard drive), it perform much much better and faster. 

What make me confused is, the external hard drive is a 3.5 inch 7200 rpm SEAGATE hard drive which have lower read/write rate compared to internal Macbook Air M1 SSD hard drive.

When i check at Mac activity monitor apps, the CPU percentage of Adobe Bridge software is more that 200% when using internal harddrive, while when using external harddrive it is just around 60%.

Hope anyone that have more technical experience can help me solve my problems.

Thank you in advance.