The latest release of Excel is focused on performance improvements. The main areas that have been addressed are RealTimeData functions, faster opening of workbooks with many user defined functions and faster aggregation.
RealTimeData functions (RTD) are commonly used to update a spreadsheet from a real-time data source. For example, if you have a stock portfolio you can add RTD functions to your sheet to provide real-time prices: as the stock moves, the price in the Excel cell is updated automatically:
Microsoft has removed bottlenecks in the underlying memory and data structures and also made it “thread safe”. The result is a significant performance improvement on sheets with lots of RTD functions.
I have noticed with one of my testing spreadsheets, with lots of RTD functions, that Excel now consumes less CPU and is generally more responsive.
User Defined Functions (UDFs) are custom functions that can be created by users or provided by an Add-in to add additional functionality to Excel. These functions operate the same as regular functions/formulas.
Opening workbooks with many UDFs was previously very slow as Excel looked up each UDF on the sheet. Now, Excel includes a UDF cache to make this process much faster.
Aggregation functions like SUMIFS, COUNTIFS, AVERAGEIFS, MAXIFS, MINIFS are some of the most commonly used Excel functions. With the latest release of Excel the performance of these functions is drastically improved.