Nothing is gonna make TWS run "Fast". The "slowness" with TWS is a data feed issue and fetching charts.
4k probably too large for 17" without scaling. Go with the HP. I've had 4 Thinkpads and my current HP Elitebook G5 and the HP is definitely the best laptop I have ever had. The first two Thinkpads were good, but they went downhill over the years after Lenovo acquired it.
I'm curious about your Excel workbook and can't help but think that what you're doing is not suited for Excel? I don't have a live stream through Excel, but I do use Excel as a front-end for my data-analysis (SQL DB and C# application) and either Excel isn't sufficient for this OR the application is built poorly. But I know I've optimized the current solution as much as possible, so for the future and a rebuild I may opt to use some other software than Excel. Regardless, I'm also in the market for a new laptop with similar requirements (except for the 4K screen), so would be interested in hearing what you decide on.
If lightness is your thing and want 17" then it's hard to beat the LG Gram range although it won't be as powerful as a specialised gaming type laptop.
Yes, as I wrote earlier ITT, the real source of the problem is that I'm using Excel for something far more resource-intense than it was designed for. I know that if I wanted to take the "next step" in my trading, it would involve ditching Excel in favor of a custom-built API solution, but that would be very cumbersome and costly. What's dissuading me from the HP are: 1) Diagnostic tests suggesting that it's performance lags far behind what its specs would imply 2) Lack of Thunderbolt 3. << The much bigger drawback for me, prob a deal-breaker in fact. I run multiple 4K@60hz monitors, which I don't think is possible with non-TB USB-C. And various portable displays I've tried also need TB. Pretty sure LG doesn't make a 17" 4K version of the Gram.
I nearly always use HDMI or TB3 out-ports (with TB/USB-C to HDMI male-to-male cable) to drive my 4K@60hz displays. Are there cpu-performance arguments for using DP? I.e. from what I've read, DP can support higher refresh-rates, but does it also result in performance improvements for the non-display processes a cpu is running? In short, if I'm fine with what I'm seeing on my external monitors using current HDMI/TB3 (which I am) are there nonetheless reasons I should switch to DP?
What's your CPU utilization when you're running Excel for your 500 calculations? Did you know you can run multiple instances of Excel? Could you run 250 in one instance, and 250 in another? I know it's possible, but would that work for your purposes?
Sorry should have been more clear. As long as you are running HDMI 2.0 or higher it is very similar, but a lot of laptops are stuck at HDMI 1.4. I don't think there is any CPU-GPU performance issue. On a side note, I have seen several monitors that claim higher refresh rates, but don't look as crisp when they "overclock" or are set to above 60hz.
I thi k your old machine specs were more than powerful enough. TWS is very bad. I don't think you can make it go any faster. I've tried. (Using a 6 year old laptop,16GB Ram, i7, with 3 screens total. - using more apps, more software than you x3 at least in parallel. Having zero issues, and great performance.)