Probably you dealing with a very large Excel file.
You could try the component tFileExcelSheetInput or tFileExcelSheetOutput with tFileExcelWorkbookOpen.
The last one is able to create a streaming excel workbook (called memory saving mode) which holds not all records of the excel file but only a smaller number (default is 100). This way you can process very large excel files with a small memory footprint.
http://www.talendforge.org/exchange/index.php?eid=623&product=tos&action=view&nav=0,1,1
tFileExcelWorkbookOpen -> tFileExcelSheetInput ---> .... process your flow...
I have introduced the memory saving mode because I run in the same issues you currently have
😉
The disadvantage of the memory saving mode is you cannot read randomly in the workbook, you have to process the rows when you receive them.