add a cache on getEstimatedFees too

src/api/Fees.js

@@ -1,5 +1,6 @@
 // @flow
 import invariant from 'invariant'
+import LRU from 'lru-cache'
 import type { Currency } from '@ledgerhq/live-common/lib/types'
 import createCustomErrorClass from 'helpers/createCustomErrorClass'
 import { blockchainBaseURL } from './Ledger'
@@ -11,10 +12,20 @@ export type Fees = {
   [_: string]: number,
 }
 
+const cache = LRU({
+  maxAge: 5 * 60 * 1000,
+})
+
 export const getEstimatedFees = async (currency: Currency): Promise<Fees> => {
+  const key = currency.id
+  let promise = cache.get(key)
+  if (promise) return promise.then(r => r.data)
   const baseURL = blockchainBaseURL(currency)
   invariant(baseURL, `Fees for ${currency.id} are not supported`)
-  const { data, status } = await network({ method: 'GET', url: `${baseURL}/fees` })
+  promise = network({ method: 'GET', url: `${baseURL}/fees` })
+  cache.set(key, promise)
+  const { data, status } = await promise
+  if (status < 200 || status >= 300) cache.del(key)
   if (data) {
     return data
   }