在PowerShell脚本中降低excel com对象的性能

I have witten a powershell script that creates an excel com object to repeatedly read *.csv files, generate a graph, and then save the the graph as a *.pdf file. The code segment is shown below. When the script starts, it takes between 2-4 seconds per file. The longer the script runs, the longer it takes to process an individual csv file. After about 1,000 files, it takes about 60 seconds per file. All of the csv files are small 2 columns by 70 rows. When I have 215 graphs to generate, it takes about 12 minutes to run. When I have 1,522 graphs, it takes over 20 hours. Is there something I can do to speed this up?I have witten a powershell script that creates