I have a problem after loading external models to google earth.

I have a project of several buildings and other objects located in a small
area. I did the modeling in sketchup and separated the project to several
files; where each file contained a single model (component) repeated
several times to minimize the KMZ size. I had 10 files in the end.

I uploaded the files to google earth as external models and it uploaded in
a relatively good speed (no complains here). But when I try to orbit and
pan using the mouse between the models while all the models are visible in
the screen area I get a slow movement.

When I zoom in near the models the movement improves and becomes smooth.

Although in google earth itself there are too many models in a small area
like New York city, you don’t notice any slowness in the movement.

Can anyone help me and tell me why is this happening? I need to fix this
problem and make the movement smooth regardless of the number of external
models I upload.