As I said, the history graph is not that important on a portable device.
The issue I am deeply concerned about is the entity view because there is nothing I can do to limit the displayed number before the page is loaded. If I could apply a filter and then click submit then I could limit the list.
But listing an html table with 700 lines on an iPad is not a big challenge for a browser. It is the fact that each line is an active element that fetch data and it seems to kill the rendering engine.
On a stationary computer you can see that the browser works hard. The html loads in 0.4 seconds and the. It takes around 6 seconds to load the data. And this is on an i7 with loads of RAM and gigabit Ethernet. The HA machine is also a real computer and not a Raspberry pi.
The entity page has become really heavy and for a mature installation like mine, it kills IOS Safari browsers. As I said 700 entities. Remember many devices represent many entities. A single Philips Hue motion sensor is also a light sensor, temperature sensor, and battery sensor. Each window and door sensor reports battery and temperature. Each Philips remote is a battery sensor and there is an automation associated with each button and long press. So that is at least 9 entities for a Philips remote. It quickly adds up. I have around 35 zigbee lights. I have around 15 MQTT type devices with multiple entities each. The Unifi integration adds all devices on the Wifi as an entity. . And 7 Amazon Echos and 7 Google Homes. An Apple Tv, a Samsung TV, a Kodi box. Two sirens. Two smoke alarms. It adds up quickly. Around 400 entities are device related. And around 300 automations. It sounds big but really it is not. You will all end there within a year if you are just a little serious about home automation. And we all are, right? Otherwise we would just have a Hue bridge and a couple of Echos.