Add longer validation time cause to changelog

Add longer validation time cause to changelog

CHANGELOG.md

@@ -1,6 +1,6 @@
 # Lotus changelog
 
-# v1.21.0-rc2 / 2023-03-21
+# v1.21.0-rc2 / 2023-03-29
 
 This is an optional but highly recommended feature release of Lotus. It includes numerous improvements and enhancements for node operators, ETH RPC-providers and storage providers.
 
@@ -13,7 +13,8 @@ Before upgrading to this feature release read carefully through these bullet poi
 - **Storage Providers:** The proofs libraries now have CUDA enabled by default, which requires you to install (CUDA)[https://lotus.filecoin.io/tutorials/lotus-miner/cuda/] if you haven't already done so. If you prefer to use OpenCL on your GPUs instead, you can use the `FFI_USE_OPENCL=1` flag when building from source. On the other hand, if you want to disable GPUs altogether, you can use the `FFI_NO_GPU=1` environment variable when building from source.
 - **Storage Providers:** The `lotus-miner sectors extend` command has been refactored to the functionality of `lotus-miner sectors renew`. The issue where extions did not work has been fixed in this release candidate.
 - **Exchanges/Node operators/RPC-providers::** Execution traces (returned from `lotus state exec-trace`, `lotus state replay`, etc.), has changed to account for changes introduced by the by the FVM. **Please make sure to read the `Execution trace format change` section carefully, as these are interface breaking changes**
-- **Syncing issues:** If you have been struggling with syncing issues in normal operations you can try to adjust the amount of threads used for more concurrent FMV execution through via the `LOTUS_FVM_CONCURRENCY` enviroment variable. It is set to 4 threads by default. Recommended formula for concurrency == YOUR_RAM/4 , but max is 128.
+- **Syncing issues:** If you have been struggling with syncing issues in normal operations you can try to adjust the amount of threads used for more concurrent FMV execution through via the `LOTUS_FVM_CONCURRENCY` enviroment variable. It is set to 4 threads by default. Recommended formula for concurrency == YOUR_RAM/4 , but max is 128. If you are a Storage Provider and are pushing many messages within a short period of time, exporting `LOTUS_SKIP_APPLY_TS_MESSAGE_CALL_WITH_GAS=1` will also help with keeping in sync.
+- **Catching up from a Snapshot:** Users have noticed that catching up sync from a snapshot is taking a lot longer these day. This is largely related to the built-in market actor consuming a lot of computational demand for block validation. A FIP for a short-term mitigation for this is currently in Last Call and will be included network version 19 upgrade if accepted. You [can read the FIP here.](https://github.com/filecoin-project/FIPs/blob/master/FIPS/fip-0060.md)
 
 ## Highlights