I am primarily an option buyer. I fire intraday orders on Nifty, Bank Nifty & FinNifty ITM options everyday (25 lots each) executed via tradingview webhook on Dhan platform. It has been super smooth since I started these except for
- a recent occasion where an intraday order was not fired. This could be an issue with TV alert server or Dhan webhook server. Not sure.
I also fire positional orders (now nearly a year) - entry, profit booking etc on Nifty again via tv webhook to Dhan. This also goes butter smooth except
- few instances where I was trying vertical spreads. Dhan had brought out hedge break alerts in their RMS which prevents the hedge leg from being exited first if there is an open short leg against it. Even when I was firing the order in the proper sequence it was failing sometimes. This was reported to Dhan and hence been taken care of.
Just to give you an idea of the speed here (tv to dhan to exchange and back) are few snapshots taken at 3:15 when there is probability of more bandwidth congestion. There is only 1 sec delay and this includes the time for the request to go from tradingview server to Dhan server and from their to the exchange via there RMS.
TV alert time - 15:06:38 today

Dhan order execution time 15:06:39

I also developed recently option selling strategies and I fire orders from their web app, mobile app, option trader app, direct API etc from watchlist, option chain, strategy builder, my custom server etc and never faced an issue with speed.
Orders also go into MCX from my new commodity trading system with limit orders being placed from mobile or web without ever facing any lag issues.
Having said these I am aware of recent user posts in Dhan with issues related to order placement during instances with volume spikes. Dhan had acknowledged the bandwidth congestion at their end and scaling up is in progress as communicated by their community mods.
Dhan provides chat support and ya the frontend guys recently where not going beyond standard responses. This was escalated and since then there is more pro activity like quick direct calls if chat doesn’t address the issue. Before the advent of discount brokers there were relationship managers and for me atleast they were the go to guys in case of a problem. With discount brokers RMs vanished and now we are relying on chat, email, community support to address our issues. I had spend 5 yrs with the current top broker and while the community mods have been pretty prompt there is nothing to envy about the support backend. Besides they cramped and restricted my freedom to trade which is why I jumped to a broker who listens to the customer.
Bottom line am not seeing any execution speed difference between Dhan and Zerodha. This is my verdict after firing 5287 orders in Dhan platform. Tech will have issues. As long as it is acknowledged and fixed I don’t have an issue. Besides support is better and in product development Dhan follows a bottom up approach and brings out new features fast. So I plan to stick with Dhan only unless and until they screw up bad or until there is someone who is significantly better.
Thanks to Dhan now am able to fire kichdi of strategies in auto mode and achieve better monthly consistency
+
aaj ka on an expiry day where orders went through without any glitches for me (Dhan did have issues today with a line to NSE flipping )
Another thing to note is that the bad in Dhan community about Dhan stays there unlike certain familiar forums where it is flagged, hidden etc 
What exactly are the issues you are facing ? What do you trade - stocks or fno ?